As a person that has rebuilt a lot of diffs in different vehicles, this is not a job I would be doing with it still in the vehicle.
There is a collapsible spacer behind the flange and that sets the preload on the pinion bearings. You have to have the diff out to set that up correctly. Doing a seal change in the vehicle makes it absolute arrse to get the preload correct.

Good luck if you get away with it.

PK