2004 MERCURY MOUNTAINEER - Transmission, Transaxle Automatic Transmission, 5R55S, 8 Cylinder 4.6L, 4x4, 60 Months Warranty. Free Shipping, 1 Month Return Policy. Used (Original Equipment Manufacturer). Transmission Tested and Run, covered by warranty. All Transmissions are Shipped as Complete Assemblies including: Transmission; Torque Converter (Automatic Transmissions Only); Oil Pan.