This procedure applies to the A-230 and Overdrive-4 transmissions only. 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 rear of the vehicle and support it securely on jack stands, ensuring the front wheels are blocked to prevent rolling. A leaking seal will result in transmission lubricant buildup on the front of the driveshaft, potentially dripping from the dust shield at the rear of the transmission. Begin by removing the driveshaft, then place a container beneath the rear of the extension housing to collect any spilled oil. Carefully pry the oil seal and bushing (for A-230 transmissions) out of the rear of the transmission using a screwdriver or pry bar, taking care not to damage the splines on the transmission output shaft. To install the new oil seal, use a large section of pipe or a very large deep socket as a drift, driving it into the bore squarely and ensuring it is completely seated. Finally, install a new bushing using the same method.