Clean CARFAX. Priced below KBB Fair Purchase Price! 2011 GMC Sierra 2500HD SLE 4WD Fire Red Allison 1000 6-Speed Automatic Duramax 6.6L V8 Turbodiesel Duramax 6.6L V8 Turbodiesel, Allison 1000 6-Speed Automatic, 4WD, Ebony Cloth. Reviews: * Impressive hauling and towing capabilities; refined and quiet ride; solid build quality; responsive steering; comfortable seats. Source: Edmunds * If you are a satisfied past or current Sierra HD owner, you will love these much-improved new ones despite their mostly carryover styling. Their performance, capabilities, refinement and fuel efficiency have improved, especially with their new and surprisingly quiet available Duramax turbo diesel V8. Source: KBB.com