The 2011 GMC Sierra 3500HD is the one-ton version of GMC’s heavy-duty, full-size pickup. If you want dual rear wheels or just more brawn than the Sierra 2500HD, take a good look at the 3500HD, a massive and rugged work machine that still delivers a smooth ride, comfortable cabin, and handsome exterior. Like the 2500HD, the Sierra 3500HD receives major changes for 2011. The drivetrain is now more powerful, and efficient, with an upgraded diesel engine. The frame and suspension have been strengthened to handle the increased capacities provided by the beefier powertrain and to reduce driving imperfections like noise and vibration. The changes don’t stop there, however. The optional diesel engine now uses diesel exhaust fluid (DEF) for more environmentally friendly emissions. There’s also a new two-stage exhaust gas recirculation system and selective catalytic reduction to make the Sierra 3500HD greener. Other additions include a new high-pressure fuel-injection system, a flat-panel air cartridge for improved cold-weather performance, fast-acting glow plugs that will start almost instantly in even the coldest temperatures, larger brakes, and an updated steering box. The Sierra 3500HD is available with a Regular, Extended, or Crew cab and has an available dually setup for the rear wheels. All trim variations are available with either two- or four-wheel drive. The Regular and Extended cab trims come with a long bed only, but Crew cabs are available with a standard bed (78.0 inches long) or the long bed (97.8 inches). The standard drivetrain for the Sierra 3500HD is a Vortec 6.0-liter V8 engine (360 horsepower, 380 lb-ft of torque) paired with a heavy-duty, electronically controlled six-speed automatic transmission with overdrive, electronic engine grade braking, and tow/haul mode. The preferred powerplant, however, is the optional Duramax 6.6-liter turbodiesel V8 and its 397 horsepower and staggering 765 lb-ft of torque. The turbodiesel received significant upgrades to make it more powerful, efficient, and quiet. It’s also B5-B20 biodiesel compatible. The turbodiesel is paired with a beefed-up Allison 1000 six-speed automatic transmission (the same type of transmission that drives the M1 tank) with electronically controlled overdrive, electronic engine grade braking, and tow/haul mode. Maximum payloads and towing capacities vary depending on cab, engine, number of rear wheels, and two- or four-wheel drive. The heavy diesel engine reduces payload capacity, but it does provide a significantly higher towing capacity. Properly equipped, a Sierra 3500HD with the gasoline V8 can carry a 6,635 payload, while the max payload for a diesel is 6,539 pounds. The high-end towing capacity for the gas engine is 14,500 pounds, and for the diesel it's 21,700 pounds. The upgraded suspension and fully boxed steel frame allow the Sierra 3500HD to handle those heavy loads and maintain its characteristically comfortable ride and handling. The front suspension can be adjusted by turning two bolts, which allows the truck to sit at a normal attitude even when fully loaded, reducing tire wear and providing better running clearance when plowing. There is also an available Integrated Trailer Brake Controller mounted on the dash that delivers a measured brakeforce signal to the electric-controlled trailer brakes, eliminating the need for an aftermarket device. The Sierra 3500HD is available in three trim levels – Work Truck, SLE, and SLT. The utilitarian Work Truck trims come with air conditioning, trip computer, 40/20/40-split front bench, vinyl upholstery and floor coverings, tilt steering wheel, four-speaker AM/FM stereo, and 17-inch steel wheels. The SLE level upgrades with a CD/MP3 player, XM radio, OnStar, cruise control, full power accessories, keyless entry, carpeted floor coverings, cloth upholstery, leather-wrapped steering wheel, tinted rear windows, and 18-inch polished aluminum wheels. The SLT adds dual-zone automatic climate control, heated leather front bucket seats with power adjustment, remote start, auto-dimming rearview mirror, steering-wheel-mounted cruise and audio controls, Bluetooth, foglights, automatic locking rear differential, heavy-duty trailering package, heated exterior mirrors, and an upgraded Bose stereo system with a USB port.