http://VictoryChevy.com 888-906-9328 The standard power plant for the 2012 Chevrolet Silverado 3500HD is a 6.0-liter gasoline V8 engine that produces 360 hp and 380 lb-ft of torque. A six-speed automatic is the only available transmission. The optional 6.6-liter V8 turbodiesel is surely the engine choice for those who plan on towing or hauling on a regular basis. It cranks out 397 hp and 765 lb-ft of torque and is mated to a heavy-duty six-speed automatic transmission with manual shift control. The 6.6-liter V8 is a clean-running diesel, thanks in part to a urea-injection system. If the diesel exhaust fluid (DEF) runs low, however, top speed will be limited to 55 mph. If the DEF reservoir is empty, speed is lowered to 40 mph.