GMPartsGiant.com offers the wholesale prices for genuine 2019 GMC Sierra 3500 HD 4WD parts. Parts like Brake Lines/Rear are shipped directly from authorized GM dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 8 Cyl 6.0L, 8 Cyl 6.0L Flex, 8 Cyl 6.6L Diesel. Model Code: 3500 CREW CAB LONG BOX, 3500 CREW CAB ONLY, 3500 CREW CAB STANDARD BOX, 3500 DOUBLE CAB LONG BOX, 3500 REGULAR CAB.