MoparPartsGiant.com offers the wholesale prices for genuine 1999 Jeep Grand Cherokee parts. Parts like Transmission Oil Cooler & Lines are shipped directly from authorized Mopar dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 6 Cyl 4.0L, 8 Cyl 4.7L. Transmission: 4-Speed Automatic Transmission, Multi-Speed Automatic Transmission.