Unless I was to replace bearings and seals, I would not immerse that chunk in a parts cleaner vat. Just for confirmation of what's in there, get a clean glass container, dip out some of that liquid and just let it sit for a hour or so - probably be a bunch of crud precipitate out and lie on the bottom of that container. Next. reach all the way down, and if necessary due to some being pretty nasty, wear some rubber gloves - what ever is on the bottom of that vat - that's some of what will be in those nice shiny bearings - and there are at least four which can get expensive in East Overshoe on a Saturday afternoon.
Unless there is a real good reason to dunk that differential, don't - you can do a good cleaning with a bunch of rags and some spray degreaser along with a half hour of your time.