[Dave at Pelican Parts]

There should be no way for gear oil to get into the middle of the output flange. There will be plenty of CV joint grease there, but that isn't gear oil.

I know professional mechanics who insist that the cardboard-type gasket must be used between the flange and the joint, and others who prefer not to use it.

Replacing the output seals can be done with the engine/trans still in the car. But it's easy to drop the trans off the engine, so consider if working upside down under the car is more of a pain than removing the trans and working on the bench.

Basically you will need to hold the flange still and remove the big bolt in the middle of it. Then pull the flange out, pull the seal out, drive the new seal in, and bolt up the flange again. You will want to make sure everything is clean and free of scratches, too.

--DD