Oil leaks can be found to originate from the extension housing Automatic Transmission Output Shaft Seal which is rather common to get worn and it is not very difficult a task to get replaced with the transmission still in the vehicle. The extension housing of the Automatic Transmission Output Shaft Seal can be found near the back end of the transmission close to the driveshaft coupling. First, place the car on a lift and make sure it is properly blocked using jackstands. Next, remove the driveshaft. If available this task is best done with puller or seal removal tool, to remove the Automatic Transmission Output Shaft Seal from the rear of the transmission gently with extra precautions to avoid damaging the splines of the output shaft of the transmission. To fit the new Automatic Transmission Output Shaft Seal, you can use a big portion pipe or a very big deep socket as a drift by hitting the latter until it is well driven into the bore of the shaft to a good concentrate. Light weight grease should be applied to the splines of the transmission output shaft and the outer side of the slip yoke for the driveshaft before reinserting the new driveshaft being careful not to exert too much pressure to damage the lip of the new seal. Last, look at the level of the lubricant in the transmission and add if it is low.