General Motors has jumped back into the serious towing arena big-time with the introduction of its 2001-model Chevrolet Silverado HD and GMC Sierra HD trucks, including 2500- and 3500-series pickups in standard, extended-cab and Crew Cab models — all of which arrive at dealerships this fall. Tow ratings for the new trucks will range up to 12,000 pounds for travel trailers and 16,000 pounds for fifth-wheel trailers. The venerable GM 7.4-liter V-8 is being replaced by an all-new Vortec 8100 (8.1-liter) V-8 rated at 340 hp and 455 lb-ft of torque. On the diesel front, there’s an all-new Duramax 6.6-liter turbodiesel engine rated at 300 hp and 520 lb-ft. The direct-injected, intercooled Duramax diesel is a joint venture between GM and Isuzu Motors, and will be built at a new manufacturing facility in Moraine, Ohio. The current model 6.0-liter Vortec engine is available as the standard powerplant in the 2001 truck models. Transmissions for the new big-block and diesel engines include an Allison 1000-series five-speed automatic with overdrive that’s rated to handle up to 375 hp and 575 lb-ft of torque; gross vehicle weight rating (gvwr) is 19,850 pounds and the gross combined weight rating (gcwr) is 26,000 pounds. In addition, the big engines can also be optioned with a new ZF-S6-650 six-speed manual transmission that is designed to easily handle the 12,000-pound gvwr and 22,000-pound gcwr of the new GM HD trucks.