Heavy-Duty Trailering Equipment, Max Trailering Pack (4.10 Rear Axle Ratio and Heavy-Duty Rear Automatic Locking Differential), Vortec 6.0L V8 SFI VVT, 4-Speed Automatic Super Duty, and 4WD. Looking for an amazing value on a terrific 2008 GMC Sierra 1500? Well, this is IT! Leave all the pavement-locked crowds behind with the off-road ability of this Sierra 1500 SLE1. The Sierra 1500 scored the top rating in the IIHS frontal offset test. Buy from the people you know and trust. DEFINITELY DELLENBACH!!!!