I've purchased from FCP Euro, Pelican parts, ECS Tuning and Turner without issue. My go to shop is Bimmerbum though. As far as I know, they are still...
Please remember to use thread sealant (not locker) on the two larger horizontal bolts that hold the rear main seal carrier...Many folks forget to do...
Do the torque converter seal on the front of the trans. and think about the shift shaft seal too as its another one nigh on impossible with trans in...
Not at all a long shot. Aerated fluid makes perfect sense. Could just be the pump cavitating from a restriction somewhere or a seal like yours was.
...