MoparPartsGiant.com offers the wholesale prices for genuine 2020 Ram 3500 Pickup parts. Parts like Differential Pressure System 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, 8-Speed Automatic Transmission.