GMPartsGiant.com offers the wholesale prices for genuine 2021 GMC Sierra 3500 HD 2WD parts. Parts like Transmission Vent Hose 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: CREW CAB 6'6" BOX 1 TON, CREW CAB 8' BOX 1 TON, EXTENDED CAB 8' BOX 1 TON, EXTENDED CREW CAB 1 TON CHASSIS 161.5, REGULAR CAB 1 TON CHASSIS 137.0, REGULAR CAB 1 TON CHASSIS 161.5, REGULAR CAB 8' BOX 1 TON.