So firstly, a massive thanks to Chris, Babs, Eren, and Hayden for all their help and offerings of help. Made me feel all warm and fuzzy inside. Thanks heaps guys

Second, car is back in Sydney. Went to pick it up today with dad.

It's not a hole, it is merely a viewing window.

But yeh, upon closer inspection it looks like an exit wound, so I expect something has come loose inside, got caught up in diff center and been spat out at the casing and shot through. Kinda cool actually. Ive considered just replacing it with another diff in the mean time, but because I have this stupid brace on the back it means taking out the alignment bolt and getting another wheel alignment. So the car is just going to have to sit in the garage until about July when I can afford a Torsen diff.