MoparPartsGiant.com offers the wholesale prices for genuine 2003 Dodge Ram 3500 parts. Parts like Transmission Oil Cooler & Lines 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 5.7L. Transmission: 4-Speed Automatic Transmission, 5-Speed Automatic Transmission, 5-Speed Manual Transmission, 6-Speed Manual Transmission.