MoparPartsGiant.com offers the wholesale prices for genuine 2020 Ram 5500 parts. Parts like Underbody Shields And Plates 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 6.4L. Transmission: 6-Speed Automatic Transmission.