hey there, buy urself a chevy duramax 2500hd! i have a 2004 lly 4door crew cab and i pull a 40' tri axel toybox 5th wheel with 2 full size quads/ or 2 harleys and my 18' fiberglass boat behind and i get 12 mpg pulling , and 17.2 empty. the stock truck puts out more horsepower and more torque...