The 2005 Chevrolet Silverado 2500HD 4 Dr Work Truck Extended Cab SB HD 4WD has a 6.0 L, 300 hp V8 powertrain with standard 5 speed manual transmission.  This trim has 4 doors, seats 6, and offers standard air conditioning and ABS brakes.  Cd player comes as an option.  Max towing capacity comes out to 15600 lbs.