GMPartsGiant.com offers the wholesale prices for genuine 1999 GMC C1500 parts. Parts like Fuel Tank And Mounting 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. Model Code: C1500 EXTENDED CAB STANDARD BOX.