Towing power reigns supreme in the 2004 GMC Sierra 3500, the one-ton offering in the pickup lineup. With the highest tow rating (up to 12,000 pounds) and a payload capacity ranging from 3500 to 5500 pounds, the Sierra 3500 takes no prisoners, but it can take a lot of cargo. New this year is a Work Truck trim, which is minimally equipped. Next up is the Base, which gets chrome grille and bumpers this year. The SLE receives standard foglights and adds leather seats to its options. The upscale SLT has a CD changer, leather seats, and power driver's seat. The Work Truck comes in Regular Cab only, which features one row of seats and fits three, while the other trims also offer Extended and Crew Cabs, with longer wheelbases and two rows of seats for up to six passengers. Crew Cab doors are conventional, while the rear doors on the Extended are more narrow and don't open independently of the front ones. Engine choices range from the standard 6.0-liter, 300-hp V8 with either a 4-speed auto tran or 5-speed manual, to an 8.1-liter, 330-hp V8 with 450 lb-ft of torque. There is also a powerful 6.6-liter turbodiesel Duramax that delivers 300-hp and 520 lb-ft of torque. The latter two engines come with either a 6-speed manual or 5-speed Allison automatic. Most drivers praise the Duramax/Allison combo as the best hauler. ABS brakes, dual front airbags, and 16-inch wheels are standard across the lineup. Some new options added for 2004 include a lock box under the rear seat and a choice between a soft or hard cargo cover. The 2004 Sierra 3500 earns high marks for its interior room, engine power, and towing capacity. The major gripe was with the bland interior design.