I have a bumper pull horse trailer. Fully loaded, the trailer weight is less than 7500 lbs. I have noticed that the 2004 F-150, 5.5 ft bed, extended cab trucks can tow up to 7800 lbs, while the 5.5 ft bed, crew cab trucks can tow up to 9800 lbs. Is there any difference between the two F-150 trucks in towing cababilites since my trailer weight is below the towable amount? What is the difference in towing between the 2004 F-150 and 2005 F-250 trucks for a 7500 lb trailer?