Clean CARFAX. Onyx Black 2026 GMC Sierra 3500HD Pro 4WD 10-Speed Automatic Duramax 6.6L V8 Turbodiesel 10-Speed Automatic, 4WD, Black Cloth, 120-Volt Bed Mounted Power Outlet, 120-Volt Instrument Panel Power Outlet, 2 Charge-Only Rear USB Ports, 2 Ch...