GMPartsGiant.com offers the wholesale prices for genuine 2016 GMC Sierra 3500 HD Denali 4WD parts. Parts like Automatic Transmission Oil Cooler Pipes 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.