Detailed item info Model OverviewThe GMC Sierra comes in many different configurations. 2500 versions come in one of three body styles. regular cab with a long bed. crew cab with a short bed and crew cab with a long bed. 3500 body styles mirror those options but also offer the option of two extra wheels on the rear axles. useful for towing extra heavy loads. Beyond that. both 2500 and 3500 are offered with either a 6. 0L V8 making 360 horsepower or a 6. 6L V8 turbo diesel making 397 horsepower and 765 foot pounds of torque. All 2500 and 3500 HD Sierras come with the option of having 4-wheel drive. Trim levels for the 2500 and 3500 come in three different flavors. Work truck. SLE and SLT. with SLT trim only available on crew cab versions. In standard work truck trim. the vehicle is fairly basic with automatic door locks. air conditioning and cruise control. SLE versions add OnStar. heated exterior mirrors. a leather wrapped steering wheel. power windows and a CD/MP3 player. The SLT trim includes power seats. steering wheel mounted audio controls. a remote starter. dual-zone climate control. a Bose stereo. Bluetooth connectivity and power folding mirrors. Denali versions come in only one trim level and in crew cab and short-bed. Regardless of bed length. the Sierra HD Denali is packed with luxury goodies. Standard features on the Denali include perforated leather seating surfaces. heated and cooled 12-way power adjustable front seats. a premium sound system with a 9-month subscription to Sirius XM satellite radio. a heated. leather wrapped steering wheel. auto-dimming rearview mirror with automatic garage door opener. power adjustable pedals and rear parking assist. The Denali also comes with a unique grill and other selected trim. Options across the Sierra HD range tend to be fairly utilitarian. with items such as a longer axle ratio. dual alternators and off road suspension sprinkled across the checklist of options. However more common items such as a rear seat entertainment system. a navigation system and a sunroof are also available on the Sierra HD.