GMC's light-duty Sierra trucks in half-ton 1500 models include Wideside and Sportside body styles, rear 2WD and 4WD modes, and cabs of regular and extended lengths.

But for 2004 there's more - a new 1500 Crew Cab with four full-size doors and two row of seats for up to six passengers. The Crew Cab comes in SLE or SLT trim and 2WD or 4WD and an abbreviated cargo box measuring 68 inches long. The Crew Cab Sierra draws from a Vortec 5.3-liter V8 producing 295 hp to bring down GVWR numbers of 6800 (2WD) and 7000 (4WD) pounds plus maximum trailer towing capacity of 8500 pounds.

Deluxe Sierra Denali with an all-wheel-drive (AWD) system stocks Delphi Automotive's Quadrasteer, which controls the direction of rear wheels so all four wheels work together more efficiently than when only the front ones turn. Vortec V8 engines in the series range from a base 4.3-liter plant at 200 hp and 4.8-liter at 285 hp to the 5.3-liter with 295 hp and a 6.0-liter V8 worth 300 hp - but in Sierra Denali it's pushed out to 325 hp.

The HD (heavy-duty) label for Sierra signifies big trucks stretched to king-size dimensions. The series shows cabs of regular and extended lengths along with the four-door Crew Cab stocking car-like comforts.

Muscular engines power these trucks to the top of the heavy-duty class, from a big-block 8.1-liter Vortec with 340 hp to a Duramax 6.6-liter turbo-diesel that musters 300 hp. Sierra in 2500 series adds a four-door Crew Cab edition in 2WD or 4WD with GVWR of 8600 pounds, and there's a new 3500 (one-ton) model with single-rear-wheel (SRW) configuration for 4WD and a long-box bed in back with all three sizes of cabs.

GMC's full-size sport-utility vehicle rides on the Sierra platform and totes Sierra powertrains that reach from a 285 hp 4.8-liter V8 to a 5.3-liter edition good for 295 hp. The 4WD Yukon uses an active transfer case and optional Autoride continuously-variable suspension.

A new tire-pressure monitoring system puts a graphic icon flashing in the instrument panel if air pressure drops below a specified level. New options include a power sunroof and DVD-driven video entertainment system with flip-down LCD screen and two sets of wireless headphones.

The XL version has the Yukon structure but with added inches in length and more power. Half-ton XL stocks Yukon's Vortec 5.3-liter V8 rated at 295 hp, while the three-quarter-ton XL gets a 6.0-liter V8 spiked to 325 hp. Further, the big-block 8.1-liter Vortec V8 at 340 hp is available for the largest XL and increases tow rating to 12000 pounds.

Quadrasteer 4WS is optional for Yukon XL 2500, and new communications and entertainment packages range from a DVD-based video player to OnStar telecommunications and XM satellite radio service. (CONTINUE...)