The TrailBlazer comes in two trim levels, LS and LT. Each is available in regular and EXT extended wheelbase lengths. Four-wheel drive is available on all models. The base engine is the 291-horsepower Vortec 4200, a 4.2-liter inline-6. The Vortec 5300 5.3-liter overhead-valve V8, rated 300 horsepower and 330 pound-feet of torque, is now available as an option on both the standard and EXT models. All come standard with a four-speed automatic transmission. The SS comes with GM's LS2 6.0-liter V8 engine, which produces 395 horsepower and 400 pound-feet of torque. It is equipped with a heavy-duty version of GM's four-speed Hydra-Matic automatic transmission, the 4L70E, and is available with two-wheel drive and four-wheel drive.For 2006, a new SS model has been added to the Chevrolet TrailBlazer lineup.