General Motors Co. will reveal in St. Louis later today the ’11 GMC Sierra Denali Heavy Duty pickup, a first-ever premium three-quarter-ton truck from the auto maker.

Like the Chevrolet Silverado HD introduced at last month’s Chicago auto show, the Sierra Denali HD arrives this summer on an extensively redesigned chassis and includes an optional 6.6L turbocharged Duramax diesel V-8 engine revamped for ’11.

The Sierra Denali HD’s introduction at the National Truck Equipment Work Truck Show also reveals specifications for the new Duramax diesel for the first time. According to GM, the engine will make 397 hp at 3,000 rpm and 765 lb.-ft. (1,037 Nm) of torque at 1,600 rpm. GM claims segment-leading power with the new diesel.

But as a Denali edition, the Sierra will receive unique styling elements, such as a 4-bar chrome grille with round air inlets; body-color bumpers; chrome door handles; and a choice of 18-in. or 20-in. polished forged-aluminum wheels.

A standard GMC Sierra will be made available, as well. The Denali version comes exclusively on a 2500HD chassis and a 4-wheel-drive crew cab standard box configuration.

The all-new chassis is the first for GM’s heavy-duty lineup since 2001, and more than 60% of the part numbers for the Duramax diesel are new. The diesel powertrain also receives a strengthened Allison 1000 6-speed automatic transmission.

GM will build the Sierra and Silverado heavy duties at assembly plants in Flint, MI, and Fort Wayne, IN. Pricing will be released later.

Both trucks receive a 6.0L Vortec gasoline engine mated to a 6-speed automatic transmission that makes 360 hp and 380 lb.-ft. (515 Nm) of torque as standard equipment.