The 2006 GMC Sierra 1500HD is part of the model's second generation. This full-size, heavy-duty pickup truck is available in three trims — SL (base), SLE1, and SLE2. It's powered by a 6.0-liter V8 engine that produces 300 horsepower and 360 lb-ft of torque. Mated to a four-speed automatic transmission, the truck provides rear-wheel drive with an optional four-wheel drive. The four-door crew cab body style offers seating for up to six occupants, and it includes standard features such as air conditioning, power windows and locks, and a CD stereo. Safety highlights for the 2006 Sierra 1500HD include antilock brakes and front airbags. The model year did not introduce significant changes compared to the 2005 version.