GMPartsGiant.com offers the wholesale prices for genuine 2004 GMC Sierra 3500 4WD parts. Parts like Lamps/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 6.6L Diesel, 8 Cyl 8.1L. Model Code: 3500 REGULAR CAB.