DETROIT - With the white stuff finally falling on cities used to snow-covered roads earlier in the winter, plow-equipped trucks that make up a $20 billion annual industry are coming out to play. Only the GMC Sierra HDpickup offers the flexibility of an adjustable torsion bar front suspension as part of the industry's most-comprehensive plow prep package.

"For plow operators, our torsion bar independent front suspension is a major differentiator," said Sierra ride and handling engineer Chris Bither. "Our competitors' beam axles can't match it for traction on uneven surfaces and axle hop reduction."

Front axle loads of all types were a major consideration when engineers set out to design the current generation of Sierra HD pickups, including 2500 three-quarter-ton and 3500 1-ton  models. Torsion bars can be adjusted with a single wrench in just minutes to provide proper wheel alignment when the weight of a plow - as much as 1,000 pounds - is added to the front of the vehicle.

At the rear of the truck, 3-inch-wide asymmetric leaf springs are designed to deliver strong traction and support heavy loads like salt-spreading equipment.

All four-wheel-drive Sierra HDs are available with an optional plow prep package, which includes 10-amp power for back-up and roof emergency lights, a heavy-duty 160-amp alternator (or dual 125-amp units for diesel models), a high-flow front bumper, a forward wiring harness, a trailer brake wiring harness, a skid plate, and a high capacity air cleaner with auxiliary transmission oil cooler, all covered under GMC's standard warranty.

By contrast, a prep package for the Ford Super Duty offers an uprated alternator and heavy duty springs. The Ram's package includes 180-amp alternator and a skid plate. GMC offers   the only plow prep package for light-duty pickups.

"Even the smaller details of Sierra were designed with plowing in mind," added Bither, "Our optional 17- and 18-inch all-terrain tires were developed for excellent snow traction." All-terrain tires are available for most Sierra models as a $200 option.

Designing Sierra for serious work didn't come at the expense of handling and comfort.

 "Our new trucks hold a plow and sander with very little sag at the wheels," said Andy Ryder, who owns JAMS Lawn Care in Bangor, Maine, and uses only Sierra HDs in his fleet.  "But Sierra's seat comfort, ride, and handling are what keep us happy. And the power and performance when plowing is awesome."

Whether equipped with a Duramax 6.6L turbodiesel or a 6.0L gasoline V-8 engine, all four-wheel-drive Sierra HD pickups are rated to handle commercial-size straight and V-type plows, where Sierra 1500 models are recommended for use with personal straight blade plows up to 7.5 feet in width.