Topped with three new exterior colors for 10 total choices, the 1999 GMC Sierra 3500 Crew Cab is available in a very basic SL, a better-equipped SLE or a richly-appointed SLT trim. Power brakes with four-wheel anti-lock braking is standard for all models. On Sierra 3500 Crew Cab models fitted with the SLE trim, AM/FM cassette player, cruise control and air conditioning is added for additional comfort over the lightly-equipped SL-trimmed truck. Base engine power is provided through a 5.7 liter Vortec V-8 engine generating 255 horsepower and 330 pounds-feet of torque. Optional powerplant choices are also furnished with availability of a 7.4 liter, 290 horsepower V-8 and a 6.5 liter turbodiesel V-8 capable of producing up to 430 pounds-feet of torque. A five-speed manual transmission is found standard on the 1999 GMC Sierra 3500 Crew Cab while a four-speed automatic gearbox is optional. Equipped with either rear wheel or four-wheel drive, the 1999 GMC Sierra 3500 Crew Cab also features an optional dual rear wheel version.