Took it to Nella Enterprises in Streetsboro and got it up on the lift. The owner/mechanic was pretty cool. Listened to what I had to say.
Discovered why the seals failed. I installed them perfectly, so says the mechanic. But the pinion bearing was worn and loose. Found a not-so-nice present on the end of the drain plug.
That’s a lot of shavings!
Which meant these were all junk.
Replaced all of the bearings with a set from G2 @ Summit Racing. My driveline vibration is gone!
It was money I didn’t want to spend, but money well spent.