If you are trying to seal the 3rd member to the housing go to your local Toyota dealer's parts department and ask them for a tube of their transaxle case sealer. It's expensive, approx $16 retail for what is a pretty large tube, clean both mating surfaces with either brake kleen or some kind of alcohol based cleaner, let it dry and then apply a thin bead on one of the surfaces per the instructions. Most importantly let it dry for 12 to 24 hours before adding the gear
oil. It will not leak. Also make sure your vent is clear and that your leak is not blowing back from the front seal. Frank