Dear Brutus, I have owned several 3.42 rear axle ratio Chevy Silverados with the 350 Automatic. I put mostly 400 highway miles a week on my truck. I constantly checked my mpg and it averaged everytime 15-16 mpg. I currently own a 3.73 exact same truck and probably will not go back to a 3.42 because I actually get better gas mileage around 16-17 mpg but rarely under 16 mpg. I find that the 3.73 rear axle ratio does not make the engine kick in to a higher rpm range as often even on slight up hill climbs in overdrive. This actually helps the engine save gas and wear and tear. It also has a little bit more pick up when pulling or off the line from a stop sign. I say get the 3.73 over the 3.42 since with the heavy duty trailering equipment package, it does not cost anything to upgrade.
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The new topic is topic #461, Chevrolet Silverado.
I put mostly 400 highway miles a week on my truck.
I constantly checked my mpg and it averaged everytime 15-16 mpg. I currently own a 3.73 exact
same truck and probably will not go back to a 3.42 because I actually get better gas mileage around 16-17 mpg but rarely under 16 mpg. I find that the 3.73 rear axle ratio does not make the engine kick in to a higher rpm range as often even on slight up hill climbs in overdrive. This actually helps the engine save gas and wear and tear. It also has a little bit more pick up when pulling or off the line from a stop sign. I say get the 3.73 over the 3.42 since with the heavy duty trailering equipment package, it does not cost anything to upgrade.