Like the regular-duty version of the Sierra and Chevrolet Silverado, the heavy-duty version has been redesigned. The 2500 and 3500 HD models are offered in two- and four-wheel drive as well as the dual rear-wheel setup known as a 'dually.' Three bed configurations are available: a six-foot, six-inch standard; eight-foot long; and the Dually long. The standard engine is a 353-hp, 6.0-liter V8. A 365-hp, 6.6-liter turbodiesel is available, which produces 660 foot-pounds of torque. It can haul up to 2,200 pounds of payload and tow a heavy trailer. The engine is punchy and not too noisy, and the Allison-sourced six-speed automatic transmission is smooth.