Oil leaks frequently occur due to wear of the extension housing oil seal and bushing (if equipped), or the speedometer drive gear oil seal and o-ring. Replacement of these seals is relatively easy since the repairs can usually be performed without removing the transmission from the vehicle. The extension housing oil seal is located at the extreme rear of the transmission, where the driveshaft is attached. If leakage at the seal is suspected, raise the vehicle and support it securely on jack stands. If the seal is leaking, transmission lubricant will be built up on the front of the driveshaft and may be dripping from the rear of the transmission. To remove the oil seal and bushing, remove the driveshaft and carefully tap the dust shield (if equipped) to the rear and remove it from the transmission. On cast iron case (heavy duty) five-speed manual transmissions, remove the nut and U-joint flange. Using a screwdriver or seal removal tool, carefully pry the oil seal and bushing (if equipped) out of the rear of the transmission, being careful not to damage the splines on the transmission output shaft. If the oil seal and bushing cannot be removed with a screwdriver or pry bar, a special oil seal removal tool will be required. To install the new oil seal and bushing, use a large section of pipe or a very large deep socket as a drift and drive it into the bore squarely, making sure it's completely seated. Install a new bushing using the same method. Reinstall the U-joint flange and nut (if equipped) and tighten the nut to the torque specifications. Reinstall the dust shield (if equipped) by carefully tapping it into place. Finally, lubricate the splines of the transmission output shaft and the outside of the driveshaft sleeve yoke with lightweight grease, then install the driveshaft, being careful not to damage the lip of the new seal.
