The GMC Sierra—sibling to GM's best-selling Chevy Silverado full-size pickup—is offered in a diverse array of configurations including Regular, Extended and Crew Cab bodies; short, regular and extended cargo boxes; two-wheel drive and four-wheel drive; and a number of style and trim variations. Of these the 3500 model is the big hauler of the bunch. Engine choices for the 3500 HD range include 6.0-liter and 8.1-liter Vortec gasoline V8s and two versions of GM's 6.6-liter Duramax turbo-diesel V8.