It's not listed as a part Frank. it doesn't show up at all or I'd have posted it already. There's no mention of it in the FSM under axle rebuild either. I only know about it as I knocked one out once when putting the shaft back in. Caused me some right grief. In the end I made a sort of slide hammer arrangement and battered it back into place. It's a sort of tin plate disc that's pressed into the end of the tube from inside the diff. If it wasn't intended to hold a quantity of oil against the seal I guess it would have had drain holes in it. I think it's dual purpose though. 1 to hold oil against the seal to keep the seal and shaft surface in a puddle of oil, 2. to prevent too much tidal wash of oil against the seal when the vehicle is inclined. Sort of like a baffle. I am very careful NOT to try and use it as a support when I put the shaft in following my experience of knocking the damn thing into the diff before now.