Allison 1000 6-Speed Automatic, 4WD, Dark Ash/Jet Black w/Leather Appointed Seat Trim. CARFAX One-Owner. 4D Crew Cab Summit White 4WD Allison 1000 6-Speed Automatic Duramax 6.6L V8 Turbodiesel Odometer is 9767 miles below market average! 60 DAY SATISFACTION GUARANTEE How... via EveryCarListed.com