GM's all-new heavy-duty trucks have finally arrived, replacing the so-called "Classic" workhorse versions that were based on the previous-generation C/K. With a slightly bolder look than its 1500 Series light-duty counterpart, the 3500HD Series Sierra is fresh from the frame up. The 3500 Series (all have dual rear wheels) models are available in Regular Cab, four-door Extended Cab, Crew Cab or Chassis Cab versions.

As with the 1500 Series, these trucks share platforms and componentry with Chevrolet's Silverado, but Sierra gets some styling and feature enhancements to position GMC as the "professional grade" truck. To that end, the Sierra rides on a chassis that sits 2 inches taller than the Silverado for added road stature. But looks and special content aside, the biggest draw for GMC's big pickup is its exceptional powertrains, outstanding payload capacity, and unparalleled towing and hauling ability. And at the heart of all this newfound capability is the engine lineup.

The Duramax 6600 is an all-new turbodiesel V8 developed jointly with Isuzu that cranks out 300 horsepower and a whopping 520 foot-pounds of torque. (That's 65 horses and 20 foot-pounds more than Ford's PowerStroke, and 55/15 over the Dodge Cummins diesels.) When it comes to gasoline power, GM leads the pack there, too. The all-new Vortec 8100 V8 puts out 340 horsepower and 455 foot-pounds of torque - both numbers eclipsing those of the V10s being offered by competitors. Even the base Vortec 6000 V8 has been juiced to 300 horses.

An electronically controlled Allison transmission boasts a patented "grade-braking" feature that automatically finds the optimum gear to supply downhill engine braking without manually downshifting, allowing you to concentrate on the road. It also touts "shift stabilization" to prevent ill-timed upshifts and downshifts, and even has bolt-on "Power Take Off" capability that allows owners to run PTO-driven equipment on-site, delivering 250 foot-pounds of continuous torque.

Save for commercial applications, the interiors are much like you'll find in GM's light-duty pickups and SUVs. With comfy seats and plenty of the latest features, the big Sierra sports a roomier cabin and extra wide-opening doors, though nothing beats a Crew Cab when taking along passengers. GM says nothing beats its new HD trucks in the numbers department, either. They've got the most power, gas or diesel, the highest GVW and GCVW payload ratings for the one-ton model, plus the most towing and hauling capacity as well.

While we're not sure if the evolutionary styling of the new Sierra carries the brute appeal of a Ford Super Duty or the big-nosed 3500-series Dodge, we do know that it'll beat them when it comes to good ol' pullin' and haulin.' Because power speaks volumes in the HD truck market, the 3500 Series GMC Sierra is sure to make a lot of noise on the sales front.