MoparPartsGiant.com offers the wholesale prices for genuine 1984 Jeep J20 parts. Parts like Shift Forks, Rails And Shafts are shipped directly from authorized Mopar dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 6 Cyl 4.2L, 8 Cyl 5.9L. Transmission: 4-Speed Manual Transmission, Automatic Transmission.