NEW GMC Sierra come with All Terrain HD Truck Concept, The concept GMC Built on an '11 Sierra 2500 crew cab body, with a 1500's five-foot, eight-inch box, the concept has a stock Duramax turbodiesel, making 390 horsepower and 745 pound-feet, like the production engine, On transmission also is stock, the Allison six-speed automatic. Thanks to the non-stock box/body combo, the concept's wheelbase is 149 inches, two inches shorter than a Sierra 2500 Crew Cab.
