Engines and modifications Sierra 2500HD V (GMTT1XX) Crew Cab Standard Bed

6.6 V8 (401 Hp) Automatic

6.6 V8 (401 Hp) 4WD Automatic

6.6 Duramax TD V8 (445 Hp) Automatic

6.6 Duramax TD V8 (445 Hp) 4WD Automatic