[Dion Hildebrandt]

When you get all of these parts in place with the proper mounts and such ,spend some time measuring up your driveline angles. I suspect you may find that they may not be at ideal angles.
I say this only because of the violence you described with the diff situation, it reminds me of the troubles I had with my car. The root cause of my issues were the engine/trans and diff were doing this ( \-/ ) as an over simplified example. I kept knocking out driveline parts until we corrected that issue.

Nothing more frustrating than chasing a problem that hides in the shadows. good luck with the car