GMC has just released pricing for its new line of 2011 Sierra HD models, starting from $27,965, while those wanting the Duramax diesel and Allison transmission combo will have to spend $36,360 – a jump of $8,395. That price is, however, the exact same number as last year’s model, which is impressive considering the improvements made for the all-new 2011 truck. As for the new Sierra Denali HD (a 2500HD 4WD crew cab), it’s set at $45,865.

With an all-new frame, the 2011 Sierra comes standard with a 6.0-liter Vortec V8 and six-speed 6L90 automatic transmission. It gets 360-hp at 5400 rpm and 380 ft-lbs of torque at 4200 rpm. A total of 90 percent of the engines torque is available from 2000 rpm allowing for a 13 percent increase in fifth-wheel towing for a total tow rating of 14,700 lbs.

Diesel models get a new 6.6-liter Duamax engine and 6-speed Allison transmission with a best-in-class power of 397-hp at 3000 rpm and best-in-class torque of 765 ft-lbs at 1600 rpm. The engine block itself is a carry-over from the past model but the majority of moving engine parts are new, as is the entire fuel system. NOx emissions are also down 63 percent thanks in part to an exhaust after treatment system that is used because it won’t interfere with the engine’s ability to create power. The Diesel Exhaust Fluid (DEF) used in the process does require refilling every 5,000 miles. In addition, the new engine is B20 biodiesel capable.

As for the new Allison transmission it has been strengthened to work with the added torque of the new engine and features an optional exhaust brake, Power Take Off and a Driver Shift Control (DSC). It’s also designed to work with the new Duramax engine to give improved fuel economy by 11 percent and GMC says to expect a fuel range of 680 miles on the new 36 gallon tank.

In addition to the fuel economy improvements, GMC claims improved acceleration with Duramax/Allison combo, resulting in a 0.3-second improvement to 60 mph and a 0.5-second improvement in the quarter-mile for a rating of less than 9 and less than 16 seconds respectively.

Like it’s Chevy counterpart, the Sierra gets a new front suspension with forged steel upper control arms and cast iron lower control arms with the new front independent suspension now delivering a 25 percent improved front axle weight rating. The new 6,000 lb rating now means a snow plow can be used on all 4WD cab models equipped with the snow plow prep package. In addition, rather than a single torsion bar like on the previous model, the 2011 gets five different torsion bar rates for five different gross axle weight ratings, allowing height adjustability in accordance with the weight of a snow plow or other accessory.

As for the rear suspension, the leaf springs are now 20 percent wider, helping to improve the truck’s rear gross axle weight rating. Now 2500 models are rated to 6,200 lbs, while 3500 models get a 7,050 rating for single wheel or 9,375 of dualies. The new rear suspension is also designed to reduce wheel hop.

Safety equipment includes StabiliTrak and Trailer Sway Control on all single-rear-wheel models as well as a new Hill Start Assist feature, that holds the truck for 1.5 seconds when leaving a stop on a hill. GMC also says that under heavy load it has reduced noise vibration and harshness (NVH) by as much as 30 percent.

All Sierra HD models will be built at GM’s Flint Assembly Plant, with retails sales beginning in June.

GALLERY: 2011 GMC Sierra HD Denali

Official release after the jump:

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The all-new 2011 Chevrolet Silverado Heavy Duty models might not look all that new and there’s a good reason for it. With tight budgets at GM as of late, the Silverado HD team was given limited funds to build the truck and so they chose to put the money where those who really need a heavy duty truck will appreciate it most. Aesthetically, the only real changes to the 2011 model are a new chrome bumper, a “power-dome” hood and a revised grille. Changes to the rest of the truck, however, are significant.

For starters, new Silverado HD models sit on new frames and come with an optional all-new 6.6-liter Duramax V8 and Allison 1000 six-speed transmission. The truck’s base tow rating is now 16,000 lbs, while a 3500 crew cab/long box can pull up to 20,000 lbs. For the record, that’s 2,400 lbs more than the RAM 3500 and 1,200 lbs more than the 2010 F-350 – although no 2011 F-350 stats are available. Maximum payload is now 6,335 lbs, well above both the Ford and Dodge, although (again) Ford claims segment-best payload… but that was before the new Silverado HD was unveiled.

With wheelbases ranging from 133.6 inches to 167.7 inches (depending on how you order your truck), along with wider front and rear tracks, the new Silverado HD delivers a smoother ride and better handling.

Chevy hasn’t given any new performance stats on the all-new 6.6-liter Duramax diesel, but has said it expects segment-best torque. The block itself is a carry-over from the past model but the majority of moving engine parts are new, as is the entire fuel system. NOx emissions are also down 63 percent thanks in part to an exhaust after treatment system that is used because it won’t interfere with the engine’s ability to create power. The Diesel Exhaust Fluid (DEF) used in the process does require refilling every 5,000 miles. In addition, the new engine is B20 biodiesel capable.

Chevy says the engine has been tested to 200,000 miles under extreme conditions, using what the engineers refer to as a “95th percentile” customer.

As for the new Allison transmission it has been strengthened to work with the added torque of the new engine and features an optional exhaust brake, Power Take Off and a Driver Shift Control (DSC). It’s also designed to work with the new Duramax engine to give improved fuel economy by 11 percent and Chevy says to expect a fuel range of 680 miles on the new 36 gallon tank.

In addition to the fuel economy improvements, Chevy claims improved acceleration with Duramax/Allison combo, resulting in a 0.3-second improvement to 60 mph and a 0.5-second improvement in the quarter-mile for a rating of less than 9 and less than 16 seconds respectively.

A new front suspension with forged steel upper control arms and cast iron lower control arms is also a part of the 2011 package with the new front independent suspension now delivering a 25 percent improved front axle weight rating. The new 6,000 lb rating now means a snow plow can be used on all 4WD cab models equipped with the snow plow prep package. In addition, rather than a single torsion bar like on the previous model, the 2011 gets five different torsion bar rates for five different gross axle weight ratings, allowing height adjustability in accordance with the weight of a snow plow or other accessory.

As for the rear suspension, the leaf springs are now 20 percent wider, helping to improve the truck’s rear gross axle weight rating. Now 2500 models are rated to 6,200 lbs, while 3500 models get a 7,050 rating for single wheel or 9,375 of dualies. The new rear suspension is also designed to reduce wheel hop.

We could probably go on forever discussing the upgrades to the new 2011 Silverado HD, so we’ll try and wrap this up with a few more important things you should know. For 2011 the brakes are larger, measuring 14-inches at all four corners while the swept area of the brake pads has been increased with 13 percent more area covered on the front rotors and 17 percent more covered on the rear. Gone are 16-inch wheel fitments, with 17s now the new base wheel, while 20s can be had on the 2500HD.  Safety equipment includes StabiliTrak and Trailer Sway Control on all single-rear-wheel models as well as a new Hill Start Assist feature, that holds the truck for 1.5 seconds when leaving a stop on a hill. Chevy also says that under heavy load it has reduced noise vibration and harshness (NVH) by as much as 30 percent.

Finally, let’s not forget the standard engine, a 6.0-liter Vortec V8 and six-speed 6L90 automatic transmission. With no output numbers yet available, Chevy does claim roughly 90 percent of the engines torque will be available from 2000 rpm and that it will allow for a 13 percent increase in fifth-wheel towing for a total tow rating of 14,700 lbs.

GALLERY: 2011 Chevrolet Silverado 2500HD and 3500HD

GALLERY: Duramax 6.6 and Allison 1000

Official release and complete model specifications after the jump:

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