GMPartsGiant.com offers the wholesale prices for genuine 1999 GMC C2500 parts. Parts like Steering Pump Assembly are shipped directly from authorized GM dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 8 Cyl 5.0L, 8 Cyl 5.7L, 8 Cyl 6.5L Diesel, 8 Cyl 7.4L. Model Code: C2500 CREW CAB, C2500 EXTENDED CAB LONG BOX, C2500 REGULAR CAB.