GMPartsGiant.com offers the wholesale prices for genuine 2021 Chevrolet Silverado 3500 HD 4WD parts. Parts like Automatic Transmission Clutch Hub Assembly are shipped directly from authorized GM dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 8 Cyl 6.6L, 8 Cyl 6.6L Diesel. Model Code: 1 TON CREW CAB 6'6" BOX 1 TON, CREW CAB 1 TON CHASSIS 137.0, CREW CAB 8' BOX 1 TON, EXTENDED CAB 8' BOX 1 TON, REGULAR CAB 1 TON CHASSIS 137.0, REGULAR CAB 1 TON CHASSIS 161.5, REGULAR CAB 8' BOX 1 TON.