I've been watching this thread since last year.
I am very curious as to why the carrier moved backwards like that.
My car is in the paint shop, so I can't go out and look. IIRC, the diff is mounted to the car at three points - One in the front, and two in the rear. In order to slide rearward that much, all three points would need to fail. Certainly not unheard of. If on fails for long enough, the other two would eventually follow.
When I get my car back together, I plan to investigate this. I will R&R each bolt for inspection of the bolt and bushing.
I will also put a jack under the diff and see if I can get it to move.
A while back I came across this differential brace. I think I will install that as well.
https://store.activeautowerke.com/co...racket-dsb-e36