This particular Sierra is a loaded AT4 model that's powered by the potent Duramax turbodiesel 6-cylinder paired with 4-wheel drive. It also boasts some desirable factory equipment, including the AT4 Preferred and Technology packages, a MultiPro tailgate, heated and ventilated front seats, and much more. Power comes from a Duramax 3.0-liter turbodiesel inline-6, rated at 305 horsepower and 495 lb-ft of torque. Output is sent to the rear or all four wheels via a 10-speed automatic transmission and a 2-speed transfer case.