Bring up the car and follow all safety precautions in relation to the position of the jackstands. This is to be done in the presence of the driveshaft universal joint where you will find some fluid draining from within the extension housing. To pull out the oil seal from the end of extension housing, there is a special tool which can be availed from the auto parts store or else, in lack of such tool, a thin blade of screwdriver or chisel may be used with great care not to harm the sealing face on the housing. It also necessary a special tool to pull the extension housing bushing out of the cylinder. Check the contact face of the oil seal on the body of the universal joint yoke for any signs of scoring or burrs which will penetrate the new oil seal; if such signs are present, replace the yoke. Scrutinize the extension housing counter bore for burrs and, in this process, use emery cloth or wet and dry medium grit sand paper or any other suitable cleaning utensil to clean burr and clean up the sand paper residue with a cloth soaked in solvent. Only if the extension housing bushing was removed, a new one has to be install, with the help of the according special tool. Weld a new extension housing oil seal also make sure that it is seated well in the counterbore hole. Lastly tighten the driveshaft, lower the car and check on the level of the transmission fluid and add if want is required.