Oil leaks frequently occur due to wear of the extension housing oil seal, which is located at the extreme rear of the transmission. To replace the seal, raise the vehicle and support it securely on jackstands, then remove the driveshaft. Using a seal removal tool or a large screwdriver, carefully pry the old seal out of the extension housing, then using a seal driver, a large section of pipe or a very large deep socket as a drift, install the new oil seal. Lubricate the splines of the transmission output shaft and the outside of the driveshaft yoke with lightweight grease, then install the driveshaft. Be careful not to damage the lip of the new seal.