The Sierra 2500 HD was the three-quarter-ton, heavy duty variant of the 2nd Gen GMC Sierra that debuted for the 2001 model year. These pickup trucks were available in both short or long bed versions, as well as with sleek Fleetside, fendered Stepside, or Sportside bed sides. The standard engine was a 6.0L V8, but other optional V8 engines were offered. In addition to the gasoline V8s, a diesel option also available. Regardless of the engine selected, manual or automatic transmission options were selectable, as well as rear or all wheel drive. Production of the 2nd Gen Sierra 2500HD ended in 2007, when the 3rd Gen GMC Sierra was introduced.