Coming off the heels of a major redesign in 2007, including exterior styling renovations, a larger cabin, improved towing capacity and improved fuel economy, this year’s GMC Sierra 3500HD remains virtually unchanged. The GMC Sierra 3500HD is available in Regular, Extended and Crew Cab configurations, with your choice of two or four wheel drive. Bed sizes also vary, depending on your needs. The standard engine for the Sierra 3500HD is a 353 horsepower 6.0-liter V8, with a 6.6-liter turbo diesel as an option. The Sierra 3500HD comes nicely equipped.