Rear transmission output seal. These are directional. The 404 997 0040 would be used for the front axle flange. Doing this job on the rear seal would normally require the following parts: 4042620073 (Lock Tab #220,) 4049940110 (Lock Tab #238,) 4114110080 (Driveshaft Gasket). When the rear flange is re-installed, make sure that the oil holes are lined up or the rear bearing will not get lubrication. We also rent the specialty tools to do this repair.