I purchased a used quad cab with the 4.7 L and the 5 speed auto. It had the 20" wheels, which the dealer traded out for me to the chrome 16's. Dynamite combo; this gives you the 4.7 L with 3.9 gears and standard wheels which == good towing (7k), good power and good mileage (16-18 HWY). I've towed tractors, horses and building materials for 3 years with no repairs. Better truck than any ford I've ever had.
The five speed auto is smooth and sure. The bed size is perfect; I wanted a quad cab with a USABLE bed and this is the best one on the market.