MoparPartsGiant.com offers the wholesale prices for genuine 1998 Dodge Ram 3500 Regular Cab parts. Parts like Vacuum Pump are shipped directly from authorized Mopar dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 10 Cyl 8.0L, 6 Cyl 5.9L Diesel, 8 Cyl 5.9L. Transmission: 4-Speed Automatic Transmission, 5-Speed Manual Transmission, 6-Speed Manual Transmission.