The 2006 Chevrolet Silverado 2500HD LT3 4dr Extended Cab 4WD SB has a 6.0 L, 300 hp V8 powertrain with standard 4 speed automatic transmission.  This trim has 4 doors, seats 5, and offers a long list of standard features that includes air conditioning, power windows, power door locks, power/leather seats, cd player, and ABS brakes.  Sunroof comes as an option.  Finally, towing capacity maxes out at 15600 lbs.