Iridium Metallic 2015 GMC Sierra 2500HD Denali 4WD Allison 1000 6-Speed Automatic Duramax 6.6L V8 Turbodiesel $1000 finance incentive is for using dealer lender. The $1000 trade in incentive is for trading a vehicle in. See dealer for details. Allison 1000 6-Speed Automatic, 4WD, Jet Black Leather. ****Please Call 423-542-4136 to confirm availability****Odometer is 22753 miles below market average!Awards:* 2015 KBB.com Brand Image Awards