Oil leaks frequently occur due to wear of the extension housing oil seal, which is relatively easy to replace 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 jackstands. A leaking seal will result in transmission lubricant building up on the front of the driveshaft and possibly dripping from the rear of the transmission. For models equipped with a rear auto-leveling suspension, turn the ignition key to the OFF position before raising the vehicle. Remove the driveshaft, then use a seal removal tool or a large screwdriver to carefully pry the oil seal out of the rear of the transmission, ensuring not to damage the splines on the output shaft. Install the new oil seal using a seal driver or a very large deep socket as a drift, driving it into place squarely and ensuring it is completely seated. Finally, lubricate the splines of the transmission output shaft and the outside of the driveshaft yoke with lightweight grease before reinstalling the driveshaft, taking care not to damage the lip of the new seal.