Clean CARFAX. Silver Birch Metallic 2009 GMC Sierra 2500HD SLE 4WD Allison 1000 6-Speed Automatic Duramax 6.6L V8 Turbodiesel Passed 125 point Dealer Inspection, Duramax 6.6L V8 Turbodiesel, Allison 1000 6-Speed Automatic, 4WD, Ebony Cloth. Reviews: * Whether purchasing for commercial construction, agriculture or recreational towing, if your needs are truly 'heavy-duty' you'll likely find those needs met with the 2009 GMC Sierra HD, which offers all of the virtues, with few of the vices, normally associated with a 'heavy-duty' truck. Source: KBB.com