GMPartsGiant.com offers the wholesale prices for genuine 2000 GMC Sierra 2500 4WD parts. Parts like Spark Plug Wiring are shipped directly from authorized GM dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 8 Cyl 5.3L, 8 Cyl 6.0L. Model Code: 2500 EXTENDED CAB STANDARD BOX, 2500 REGULAR CAB.