I see that the website says that the Workhorse Module can be uninstalled before servicing and "leaves no fingerprints." Hummmm. . . If you have to make a warranty claim, does the manufacturer ask you whether you have installed any aftermarket chip? If you did have a chip in it, what do you say?
I checked most everything, injectors,no fuel leaks,added exhaust 4" Super chip set on towing (programer out still poor) oversize tires 35" and the best I can do is 9 mpg HWY. Any Ideas? Trans not slipping, no brakes stuck. Back in the day I got 15+/- Any Ideas?
I spoke to a guy yesterday that tells me he ordered a F-250 6 liter Crew cab from Ford and had them install a "Banks System" with 4" exhaust. He gets 22 mpg hwy and 17mpg city. He generates 500 HP, runs half the temp of other trucks according to his friends with similar trucks also says the whole thing was around $2,700.00!!! Anyone hear of this system and does it work.
Gale Banks Engineering has been around for decades. They are generally reputable and even supplied the initial turbo package to GMC for the 6.2 liter diesel. As with any modification, of this magnitude, your mileage may varuy and you need to check that your vehicle will remain legal with such equipment.
The claim of 500 hp and 22 mpg hwy and 17 mpg city raises a red flag. Of course, this is 500 peak hp, and he must not be operating the vehicle much at this hp level or he would be getting very low mpg. You cannot be developing high hp without high fuel consumption.
So the claim is that with this system the engine will develop 500 hp when it is called for, but will deliver excellent fuel economy when the vehicle is lightly loaded and driven to maximize fuel economy. This is still a pretty tall order.
installing an AFE intake or any other intake won't void your warranty. we're about to put a cold air intake in my brother's truck and also decided on the afe intake (one of many positive reviews on it). search for forum reviews that's how we found out about it.
I have finally bought my neighbors "old" 2000 Ford F250 diesel. He has been infirm and driven the truck only 3000 miles in four years.It is still new in every way except for the miles.
I intend to head to the lower 48 from my home in Alaska in September either pulling a 7000# camping trailer or with a slide in camper.
The ehicle has a 3.73 rear end and I'm turning about 1850 rpm at 65 mph on cruise. I got a decent 17.4 mpg on my first tank full.
Can I do better with chipping, a large exhaust and a different filter system?
Any recommendations for whose system i should buy?
Diesel fuel just went up to over $4.00 a gallon here in Anchorage, Alaska so I want to do anything that makes sense.
Do you own a diesel? If so pick up every issue of a Diesel "builder, power and 8 lug" you can find read them throughly and pay attention to the Gas vs. diesel articles. In the gas world, yes I can agree. the more power you make, the lower your mileage will get. Diesel doesn't work like a traditional engine. The more efficiently it works and power it makes the diesel engine brings mileage as a bonus. If you drive them with the intent to get decent mileage. All these guys I know complain about poor mileage but set the cruise at 80 mph and burn their tires off around every turn. I was getting around 15 mpg stock and now with a few mods and a few more horses, I get 18-20 average. Just replace your airbox with an S&B filter and replace your muffler with a high flow one alone, you will see a difference. Depending on you and truck around 2 mpg. and should be under 500 bucks. Add some type of chip or programmer and it goes up from there but say adios to your warranty should you ever get caught. some are undectable once removed but if you put on egt sensors and pyrometers the dealer knows so go with a basic one if you do. Banks has a lot of really well developed products. that work great together..... so good luck with your search for mileage
Ask the guy at ford who does your service work which one he recommends and stands behind. Sometimes if you get a smart service guy, he (or she) will sell and install good quality parts that they can stand behind should something go wrong. S&B filters are the only filters on the market that have passed fords' filtration tests. look on their web site its all there. Some dealers will say no way to any modification. Find another dealer if so. there are good ones out there. Dont take your truck or your money to a closed minded service agent.
I have a 2004 3/4 ton Silverado 6.0 that I bought new. It has been a great truck and really no expense other that oil changes and gas. I recently got rear ended and messed my truck up pretty bad and am going to trade it in. I am having mixed feelings about what to get (Diesel or Gas) This truck got around 12 in town and as much as 15 on the highway (I live in the mountains) I have been wanting a diesel for some time but I have been reading a lot about maintenance, oil changes, diesel fuel additives (As it does snow alot up here..darn global warming), and crappy gas mileage. I have been considering buying the new GM 6.6 LMM. Do you thinkk buying one of these would be a risk or should I just stick with a gas. I also do pull a race trailer (24ft). Thank you for your time and input, I really do appreciate any knowledge you have to offer. (Oh and is 10 mpg increase in fuel mileage really that plausible?)
If you like the gas engine, I would stay with the gas. Diesel prices at the pump are a little scary right now. Not to mention that the price of the Diesel motor is about $7K more and the annual servicing cost are more also. You will never earn your money back on the cost difference. Now if your looking for power then the Diesel is the way to go as long money is not a considerations.
Hi, I have a 1995 F350 dually with the 7.3l diesel motor. It is stock and I am getting around 14 around town and 17 highway with no load. What would be the best bang for the buck I could use to increase my fuel economy? I don't really need more power and am only interested in using less gas per mile.
It is quite possible that all reported efficiency gains with aftermarket mods is due to the placibo effect.
So the best bang for the buck would be for you to drive your stock F350 as if you had just spent $1k to . . . ($4k?) on aftermarket mods and you are implementing the driving practices recommended by the producers of this gear. Don't they claim something like "their mods maximize the fuel economy gains of careful driving"?
What is the max towing of my '07 F-250 CrewCab 6.0 Diesel, Automatic. It is completely stock from factory, I am thinking of buying a travel trailer, possibilly 35 footer. I see the trailers weigh between 7,000 and 9,000 lbs, these are towable and not 5th wheel.
i've seen tuning chips ranging from $50 on Ebay to $500 elsewhere. is there a difference? does the chip significantly improve the fuel economy? does anyone have a link to any independent testing done on them? also, what about other options like cold air intakes and direct flow exhaust systems? are these things going to considerably improve my mileage as diesel soars? right now i dive my 02 tdi easy and get about 46 mpg on the average. thanks for your help and input!!!
No tuning chip or reflash of an ECU will improve mpg without risking engine damage. Just continue to drive carefully and do all maintenance on schedule.
Everyone wants a VW diesel right now; you are lucky to have one. Don't ruin the vehicle by messing with the engine controls.
A chip can improve torque and power by over-riding the mfgr's turbo boost limits and fuel program, but this will come at the expense of greater fuel consumption, not less, and risks engine damage and provides a basis for denial of warranty if you do have problems.
PS Cold air intakes have no proven benefit. "Direct flow" exhaust systems change the back pressure that the engine designers have selected, and could be at variance with state and federal environmental laws and regulations.
I guess VW diesel are deferent than every other diesel out there because everything your saying is not true of a diesel truck. I have a cummins and it is proven that all of these things will give you benefits/gains. And as long as you monitor all your important readings, EGT, Boost etc...you shouldn't have any problems. But I guess all of this could be deferent do to the nature of the vehicle. But still a diesel is a diesel. All of the factory settings are de-tuning your motor and holding it back. Because of emissions regulations and trying to be friendly to the environment. Every diesel motor made today for street use has the potential to make more power and be more efficient, but with the fuel these days and emissions they are held back. But yes if you abuse the extra power you can create there is always the possibility that you could have other components that might not be able to take it. Which is where the VW could be deferent. But every diesel truck can handle the slight gains in power if you are just looking for MPG increase and not trying to make a drag truck.
" But I guess all of this could be deferent do to the nature of the vehicle. But still a diesel is a diesel."
I just read a statement over on the F-150 MPG forum that Ford has programmed their black boxes to monitor the engine performance over time, and this would detect the fact that a chip has been installed, even if one pulls the chip before bringing it in for dealer service. If Ford has a way to discover that a chip has been used, they can void the engine and transmission warranty, i.e., refuse to fix them if they break.
I can't speak to the truth of the Ford "Black Box" capabilities, perhaps someone else has more details?
This in a way could be true. Yes there are alot of vehicles that will hold in the computer if a chip/tuner etc.. has been installed even after it has been taken out. But legally a dealer can not refuse service/warranty unless they can show the chip was the direct cause of the problem at hand. Must of them will try to blow you off and tell you alot of things just so they will not have to fix/pay for the problem. Must even if the problem has nothing to do with the tuner,chip,programmer they will use this as an excuse not to warranty your vehicle.
"But legally a dealer can not refuse service/warranty unless they can show the chip was the direct cause of the problem at hand. "
But a chip affects the way the engine and transmission are run, so they could concievably have a case that the chip caused the damage.
But think further on this. To sue them you would have to admit in a public court of law that you modified the engine control chip - did you check with the EPA to ensure you did not illegally modify your engine? It could open up more problems than solutions.
I have a 2003 Chevy crew cab duramax which I pull a 33FT fifth wheel. I normally get approx. 11 to 12 MPG. I have installed a 4" exhaust with a low flow muffler and a K&M air system. ,Now I need help to find a cheap programmer and what is the best mode of operation? Should I pull in the #1 ecomony mode, #2 pulling mode for the best MPG? I dont need the other modes. Please help, Out of fuel in TN.
I have a 2000 F250 7.3L 4x4 with a 6" lift and 35's, and get about 12mpg on a good day. I'm having a big problem with my fuel now that the price has gone almost to $5 in California. I would like to pick your brain to find out what you have done to get wuch good mileage. Having to drive from San Diego to Ventura, 380 miles round trip, is killing what little pay the military gives me. The good thing is I only drive that on the weekend. I would greatly appreciate any advice that you have. I also get funny looks when I'm driving 60-65 on the highway. Thanks again if you have any help.
Why do you want your truck to smoke? Most people on the road are going think something is wrong with it and Black Smoke doesn't equal more power, it equals over fueling which is really bad for your engine and your turbo. You see the black smoke is really unburned fuel which carrys a lot of heat through the engine and results in really high EGTs (Exhaust Gas Temps). Do you use your truck to tow any?
Have you considered a Hypertech E-CON programmer? They say users report getting 3-4 more MPG and they extra power is nice. Come to think of it since you have 35" tires you might want to look at the Hypertech Max Energy as it can also correct your speedometer if you haven't done that yet. Oh and if you don't get the results you're looking for you can return it with in 30 days and get a full refund, no questions asked.
I was considering buying a new diesel truck, but after picking myself up off the ground I'm thinking of just modifying this truck I've had since new. I only use the truck for trailering a 7,000lb Artic Fox, but we tour all over the West. What are the best things to add to this truck??? Cold air intake, direct exhaust, chip (what kind?), anything else??? and what kind of HP & torque improvement should I expect. One guy told me adding an intake and exhaust only helps 20 hp. I question whether its worth it. I only have 235 hp now (torque is okay at 500lbs) and am tired of being the slowest of the slow. I'd appreciate any and all advice here.
You could replace the turbo wheel inside the turbo housing and new wastegate. Do the air box and exhaust, it is worth it. Those two upgrades allow for all the other possible upgrades to work more efficiently and provide you with the most power with the least resistance. You see those trucks bellowing black smoke? they do not get enough air and push too much fuel. My advice is to call Banks and keep all your upgrades from one company. One of my co-workers and my Dad did their fords with all Banks products. I wish I had gone that way with my build, Mine is like one from here one from there. Good luck and let me know how you do. ps I do not work for them.
Their are black diesel smelling spots on my fifth wheel and after further looking I noticed the underside of the truck is greasy looking and now noticed what I think is fuel under the truck. I smelled it and it smells like diesel fuel....and help here guy's.....?
Hi blue, don't know anything about a duramax but if it was a IH 466 or 530 it would be a piston got hot and melted a sleeve O ring and antifreeze mixes with the oil and makes steam and cracks the oil to make black goop. good luck and hope its something simple. Chuck
Don't listen to those guys down there they don't know what there talking about yes black smoke is unused fuel and yes its will make your EGT higher but thats way you put bigger exhaust on diesel and cold air in tanks to keep your EGT down. You got 6 inch so you got nothing to worry about there realy unless you have done a turbo upgraded you shoudn't have gone any bigger then 4 inch but to late know. Some say a stock turbo doesn't perform has well has it could if you went bigger then 4 inch. Anyway back to the point no black smoke isn;t going to hurt your engine or turbo has long has you take care of it change the oil when you should you'll will be fine, yes black smoke is a sign of wasted power unused fuel but you get it from doing up grades anything along chips, programers, fueling, injectors wil make it blow more smoke. but upgraded cold air intanks and intercoolers and turbos cut black smoke. So idk what you have done to your truck but if your just starting off and all you got done is a exchast this is what i recommend, you got a 2002 see i got a 2000 same things your injection pump is a VP44 go with the Quadzila Adrenaline, Quadzilla specails on dodge diesels and the Adrenaline come with 180 extry hourse power out of the box but it is downloadable for different and bigger tunes you can put tunes in for drag racing dyno more power for pull. For example the tuner comes with a 1000 kit already installed i have the programmer in my 2000 dodge cummins and i put the next one up 2000 kit and she will get one down the road. KNOW ONE IMPORTANT WORD OF EDVICE UPGRADED THE FUEL PUMP AT THE SAME TIME!!!! Cause any programmer is going to call for more fueling that year of cummins fuel pump sucks it can and will fail and if it happens your injection pump will fry and that alone is 1,500 dollers. I went with the Airdog fuel pump system 95 serious that fuel pump will be able to push fuel up to 600 hoursepower. Know with the Quadzilla programmer and the airdog fuel system is a great start for upgrading your cummins. THe truck will run good get down the road pretty fast and OH YEAH with those two things SHE WILL SMOKE!!! Both the fuel pump and programmer ran me about 1,200 dollars all together and it was worth ever dollar. You ever her some one talk about a smoke switch its a joke and will hurt you motor know i out smoked a guy with my setup and he had a smoke switch, then i out ran him, and just the Quadzilla programmer and airdog fuel pump is all i got down to my truck by the way. If you got anymore questiuons just ask
" You ever her some one talk about a smoke switch its a joke and will hurt you motor know i out smoked a guy with my setup and he had a smoke switch, then i out ran him, and just the Quadzilla programmer and airdog fuel pump is all i got down to my truck by the way. If you got anymore questiuons just ask "
OK, I'll ask. Are you saying in your post that you got better MPG, or better power? What is the MPG with your modifications?
Hey. Im new to this and im actually looking to buy another truck, im looking into diesel pickups, chevy or gmc 2500 actually, or a ford f-250. I know and work with ppl that own diesel pickups. I get alot of different types of advice. and alot of ppl have told me if i buy a diesel and dont use it to pull or drive far then it will just get trashed because it is not mad to tool around town. I do drive 25 mins to work one way. and pull a trailer with 4 wheelers.
I basically want a diesel becasue they hold their value, and i believe that they hold up better than a gas pickup. I also have been looking into chips for more MPG . i hope you guys can help thank you :confuse:
I have a stock hight and wheels Dodge 06' Dodge Diesel 2500 4x4 QC with 103,000k, picked it up about a monthe ago. Averaging 16 mpg w/ even mix of city/highway.Was hopeing for much better! It has an AFE intake and a banks cat back. Dont think anything else, but not sure?It runs great! and Ive been easy on the throttle. The biggest thing I have noticed is the idle. As i drive the idle changes. one stop light will idle smooth as can be next stop light its like beeing in a massage chair.and everywhere in between. I have a short time left on the warranty so I am taking it back in next week to complain about idle.( they already changed lift pump,(In Tank)It was stalling at idle.Will mention mpg.But im sure they'll tell me ("yep! Thats what they get!). Any one have any suggestions on specific items I could mention to the dealer pertaining to my issues? Or any other advice like things I could check on my own? i.e. fluids,wiring?I am good w/cars(built a few 4x's)I dont have a lot of experience w/diesels.
I may be taking a job that requires a lot of freeway time and the company will buy my fuel but they want us to drive vehicles that get at least 24 mpg, typically cars. I want to use a dually because I need one to pull a 22,000# gooseneck 3-4 weekends a year (on my time). My business driving will be at 65-70 mph, generally level freeway near sea level in California. I would buy a used truck, looking for the right gear ratio and tranny, and would make whatever mods necessary to the plumbing and programming. Probably 2WD to save weight and height. 1st choice is Dodge mega cab short bed, then 6.0 or 7.3 Ford crew cab short bed. Has anybody achieved this average freeway economy? 5.9 Cummins likely more economical than the new engine? Is 3.54 a good ratio for this speed? Advice on engine mods by brand names? Do I have to have a stick? Do dual wheels kill me? I don't know if I'd want to tow that much with singles, even a few times a year.
Secondary issue: I realize low numeric rear ends mean tougher towing with that big load. This would be at 55 mph, so is there an automatic that will downshift to the right gear, or should I be looking at a manual? I'd go with an underdrive or overdrive if that give the most versatility. Again, I am willing to have an imperfect towing rig to get the high mpg unloaded.
Your biggest problem is your trailer. No pickup is legally rated to pull a 22,000 pound trailer, and you would be in for some hefty fines at a weigh station. The trailer alone exceeds the combined weight ratings for almost every pickup out there. To pull something that heavy, you need at least a Class-6 medium truck.
As far as the truck itself as a daily driver, a Ram MegaCab is probably not your best option only because the 3.42 axle was only introduced in the last couple of years, and only available on the automatic for 2009. Otherwise, you're looking at the 3.73 with Dodge. I have a Quad Can 4x4 dually with 3.73s, and while I can break 20, I doubt that, even with a 2WD MegaCab over my 4x4 Quad Cab, you would be consistently able to crack 24. You'd be close.
If you truly need all the rear seat space, your best option is a Ford Crew Cab with the 7.3, single rear wheels, the shortbed if you can manage it, and the lowest-numeric axle. And again, you'd be close to your 24 mpg, but no guarantees of keeping it there.
Oops, I made a typo on the trailer weight. To simplify the post, let's forget the towing questions and just look at the possibility of getting a Megacab dually or any crew cab Ford dually past 24 mpg. Thanks for your recommendation kcram.
Ironically, you can get a brand new MegaCab dually past 24, since the 2009s offer a very tall 3.42 axle - with the double overdrive of the 6-speed automatic, you should have no trouble reaching 24 in a 2wd truck. If your budget doesn't permit "new", you can likely achieve the same going back to a 2007.5 Ram with the 6.7L Cummins and 6-speed automatic, then have the 3.42 diff swapped in.
The tallest Ford ratio is a 3.73, so you will need to look for a very light configuration... Ford does make a shortbox dually crew cab, bit they are VERY hard to find, as not many people ordered them.
Thanks kcram. So is it the 6 speed autos taller top gear ratio I am looking for and was it introduced in 2007.5, or is that when the 6.7 came out? Is the 6.7 a better candidate for a fuel economy project than the 5.9? When did particulate filters come out and are these a factor?
If fuel economy is mostly an rpm thing, why not just add an overdrive or change axle ratios on any 5.9?
The 6-speed automatic and 6.7L were introduced together in 2007.5, along with the particulate emissions equipment.
In getting the best mileage from a diesel, you want the rpm as close to the torque peak as you can get for the typical road speed... for a Cummins, that sweet spot is right around 1600-1700 rpm. But since you're driving 65-70 mph, you will need the tall 6th gear of the 6-speed automatic along with that 3.42 axle, or you would need a much older truck (12-valve mechanical Cummins from 1998 or earlier).
I had a 1996 Ram 3500 Club Cab 4x4 dually, 4-speed automatic, 3.54 axles and OEM tires (LT215/85R16E). I could get 24 mpg out of it, but to do it, I had to keep my cruise control at 55. At the same speed, my 2005 Ram 3500 Quad Cab 4x4 dually with 3.73s and LT235/80R17E tires will get around 21.
Buy the truck you want. On my Dodge diesel I mainly drive from stop light to stop light over the past few years after selling the RV trailer. Going on 90,000 miles and only opened the hood to do the oil change and replace the batteries once over the past 5-6 years. Great way to go. Just purchased the Jeep Grand Cherokee Limited with the Mercedes V-6 diesel. Tows up to 7,400 pounds. My wife also drives from stop light to stop light and has averaged over 17 MPG. Not bad for a 4,700 pound SUV. Economy of a 4 banger and power of a V-8 (376 torque rating). And the price new was $19,999.99. You can check Autotrader.com and put in zip code 75042 with a hundred mile radius to find a few of these new 2007 Jeep diesels.
Kind of a stupid question but do you have the air conditioning or the "defog/defrost" setting on? both run the compressor and cut in and out most noticeably at idle. turn the setting to vent and see if it smooths out. its a dodge thing. Mine did exactly what you described and my mech buddy reached over and turned the setting to "Hi -lo vent" and the idle smoothed right out. ......
Comments
I see that the website says that the Workhorse Module can be uninstalled before servicing and "leaves no fingerprints." Hummmm. . . If you have to make a warranty claim, does the manufacturer ask you whether you have installed any aftermarket chip? If you did have a chip in it, what do you say?
Banks Power home page
kcram - Pickups Host
So the claim is that with this system the engine will develop 500 hp when it is called for, but will deliver excellent fuel economy when the vehicle is lightly loaded and driven to maximize fuel economy. This is still a pretty tall order.
I intend to head to the lower 48 from my home in Alaska in September either pulling a 7000# camping trailer or with a slide in camper.
The ehicle has a 3.73 rear end and I'm turning about 1850 rpm at 65 mph on cruise. I got a decent 17.4 mpg on my first tank full.
Can I do better with chipping, a large exhaust and a different filter system?
Any recommendations for whose system i should buy?
Diesel fuel just went up to over $4.00 a gallon here in Anchorage, Alaska so I want to do anything that makes sense.
Thanks,
Terry
capt@gci.net
you can find read them throughly and pay attention to the Gas vs. diesel articles. In the gas world, yes I can agree. the more power you make, the lower your mileage will get. Diesel doesn't work like a traditional engine. The more efficiently it works and power it makes the diesel engine brings mileage as a bonus. If you drive them with the intent to get decent mileage. All these guys I know complain about poor mileage but set the cruise at 80 mph and burn their tires off around every turn. I was getting around 15 mpg stock and now with a few mods and a few more horses, I get 18-20 average. Just replace your airbox with an S&B filter and replace your muffler with a high flow one alone, you will see a difference. Depending on you and truck around 2 mpg. and should be under 500 bucks. Add some type of chip or programmer and it goes up from there but say adios to your warranty should you ever get caught. some are undectable once removed but if you put on egt sensors and pyrometers the dealer knows so go with a basic one if you do. Banks has a lot of really well developed products. that work great together..... so good luck with your search for mileage
Your mpg is very impressive!
So the best bang for the buck would be for you to drive your stock F350 as if you had just spent $1k to . . . ($4k?) on aftermarket mods and you are implementing the driving practices recommended by the producers of this gear. Don't they claim something like "their mods maximize the fuel economy gains of careful driving"?
Thanks
Everyone wants a VW diesel right now; you are lucky to have one. Don't ruin the vehicle by messing with the engine controls.
A chip can improve torque and power by over-riding the mfgr's turbo boost limits and fuel program, but this will come at the expense of greater fuel consumption, not less, and risks engine damage and provides a basis for denial of warranty if you do have problems.
Be happy with your 46 mpg. Don't be greedy!
thanks, jcb5
I just read a statement over on the F-150 MPG forum that Ford has programmed their black boxes to monitor the engine performance over time, and this would detect the fact that a chip has been installed, even if one pulls the chip before bringing it in for dealer service. If Ford has a way to discover that a chip has been used, they can void the engine and transmission warranty, i.e., refuse to fix them if they break.
I can't speak to the truth of the Ford "Black Box" capabilities, perhaps someone else has more details?
But a chip affects the way the engine and transmission are run, so they could concievably have a case that the chip caused the damage.
But think further on this. To sue them you would have to admit in a public court of law that you modified the engine control chip - did you check with the EPA to ensure you did not illegally modify your engine? It could open up more problems than solutions.
i have 2002 dodge ram 2500 4x4 cumins motor automatic an haz 6 inch all the way pipes ?
i have 2002 dodge ram 2500 4x4 cumins motor automatic an haz 6 inch all the way pipes ?
ps I do not work for them.
OK, I'll ask. Are you saying in your post that you got better MPG, or better power? What is the MPG with your modifications?
I basically want a diesel becasue they hold their value, and i believe that they hold up better than a gas pickup. I also have been looking into chips for more MPG . i hope you guys can help thank you :confuse:
Any one have any suggestions on specific items I could mention to the dealer pertaining to my issues? Or any other advice like things I could check on my own? i.e. fluids,wiring?I am good w/cars(built a few 4x's)I dont have a lot of experience w/diesels.
Thanks!
Secondary issue: I realize low numeric rear ends mean tougher towing with that big load. This would be at 55 mph, so is there an automatic that will downshift to the right gear, or should I be looking at a manual? I'd go with an underdrive or overdrive if that give the most versatility. Again, I am willing to have an imperfect towing rig to get the high mpg unloaded.
As far as the truck itself as a daily driver, a Ram MegaCab is probably not your best option only because the 3.42 axle was only introduced in the last couple of years, and only available on the automatic for 2009. Otherwise, you're looking at the 3.73 with Dodge. I have a Quad Can 4x4 dually with 3.73s, and while I can break 20, I doubt that, even with a 2WD MegaCab over my 4x4 Quad Cab, you would be consistently able to crack 24. You'd be close.
If you truly need all the rear seat space, your best option is a Ford Crew Cab with the 7.3, single rear wheels, the shortbed if you can manage it, and the lowest-numeric axle. And again, you'd be close to your 24 mpg, but no guarantees of keeping it there.
kcram - Pickups/Wagons Host
The tallest Ford ratio is a 3.73, so you will need to look for a very light configuration... Ford does make a shortbox dually crew cab, bit they are VERY hard to find, as not many people ordered them.
kcram - Pickups/Wagons Host
If fuel economy is mostly an rpm thing, why not just add an overdrive or change axle ratios on any 5.9?
In getting the best mileage from a diesel, you want the rpm as close to the torque peak as you can get for the typical road speed... for a Cummins, that sweet spot is right around 1600-1700 rpm. But since you're driving 65-70 mph, you will need the tall 6th gear of the 6-speed automatic along with that 3.42 axle, or you would need a much older truck (12-valve mechanical Cummins from 1998 or earlier).
I had a 1996 Ram 3500 Club Cab 4x4 dually, 4-speed automatic, 3.54 axles and OEM tires (LT215/85R16E). I could get 24 mpg out of it, but to do it, I had to keep my cruise control at 55. At the same speed, my 2005 Ram 3500 Quad Cab 4x4 dually with 3.73s and LT235/80R17E tires will get around 21.
kcram - Pickups/Wagons Host
Good luck to all