Go the websites for Ford, Chevy, and Ram, and download their trailering or towing guides. They will provide for every model with every engine size and gearing provided what the maximum towing capacity is for the vehicle.
Don't overlook the gears as the 4.10 gears on a truck or SUV will provide 25% more towing capacity than the same vehicle with 3.73 gears, and a similar gain in towing capacity and performance with 3.73 instead of 3.55 gears. People think that the higher gears will improve fuel economy and this is a myth as it does nothing for around town driving fuel economy and nothing to improve fuel economy when towing.
An extra 1 MPG when not towing and driving on a lever freeway is not nearly as important as the performance of the vehicle when towing a trailer around on flat terrain and over hilly or even mountainous areas. Lower gears also makes better acceleration when towing and for safer merging with other vehicles on the highways.
Tow package options are always a good deal and worth the few extra dollars involved.
