What does it mean to have a fully boxed, high-strength steel frame? It means that the backbone of our Heavy Duty line-up is more rigid, more durable and stronger where it counts the most.

• It allows for better suspension tuning as well as better ride quality. The frames strength has increased more than 90% and torsional stiffness by a factor of five.
• Closed sections (boxed frames) provide stronger crossmember mounting as well, for improved durability at critical joints.

The ultimate workhorse truck provides the utmost confidence to manage the heaviest of loads. The new Sierra HD lineup has it all covered with an array of control features.

• Using the engine and transmission to your advantage, Automatic Grade Braking helps slow the Sierra HD on downhill grades. It gives you more control and helps reduce brake wear.
• Includes an array of features to help you control the loads you ask it to bear, especially when trailering. Standard on all Single Rear Wheel Sierra HD models, the Trailer Sway Control works directly with Stabilitrak to identify if your trailer is swaying and uses the power of the engine as well as the braking system on the Sierra HD and the Trailer, if equipped, to bring both the vehicle and trailer under control.

• The available Duramax Diesel is a force to be reckoned with. It's more powerful, quieter, and more efficient and has best in class 397 horsepower1 and 765 lb. ft. of torque. There's nothing you can throw at this engine that it can't handle and you'll have plenty of time to try.
• GMC has beefed up the Allison Transmission in the 2011 Sierra HD to handle the increased output of the Duramax. Increased output shaft diameter, clutch capacities and improved transmission help get the truly heavy work done.

1 397hp @ 3,000 rpm, 765lb.ft. torque @ 1,600 rpm