introduces the new 2011 GMC Sierra Denali HD, the first offering of the Denali line on a heavy-duty GMC pickup Monday, March 10, 2010 in St. Louis, Missouri. The Sierra Denali HD leads a redesigned lineup of 2011 Sierra 2500HD and 3500HD trucks that go on sale in early summer — with segment leading diesel power with a new Duramax 6.6L turbo diesel rated at 397 hp and 765 lb.-ft. of torque. The Sierra HD lineup offers increased towing capability and payload supported by all-new frames and strong suspensions. (Photo by Sarah Conard for GMC)