MoparPartsGiant.com offers the wholesale prices for genuine 2003 Dodge Ram 3500 parts. Parts like Tonneau Cover 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.