MoparPartsGiant.com offers the wholesale prices for genuine 2013 Ram 3500 Cab Chassis parts. Parts like Main Shaft Assembly are shipped directly from authorized Mopar dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 6 Cyl 6.7L Diesel, 8 Cyl 5.7L. Transmission: 6-Speed Automatic Transmission, 6-Speed Manual Transmission.