Oil leaks frequently occur due to wear of the extension housing oil seal, and replacement of this seal is relatively easy, as the repair can be performed without removing the transmission from the vehicle. If a leak at the extension housing seal is suspected, raise the vehicle and support it securely on jackstands. The extension housing seal is located at the rear end of the transmission, where the driveshaft is attached; a leaking seal will show transmission lubricant on the front of the driveshaft and may drip from the rear of the transmission. Begin by removing the driveshaft. Position the shift lever into Park, if not already done, then remove the output shaft flange nut and slide the output shaft flange off the extension housing. Carefully pry out the extension housing seal using a screwdriver, prybar, or seal removal tool, taking care not to damage the splines on the transmission output shaft. Install the new extension housing seal using a seal driver or a large deep socket with an outside diameter matching that of the seal, ensuring it is driven into the bore squarely and completely seated. Reinstall the output shaft flange and nut, tightening it to the specified torque, and use a punch to stake the flange nut to the output shaft to prevent rotation, repeating the procedure on the opposite side of the flange nut. Finally, reinstall the driveshaft.