So I finally have some good news to share. They got the new rear diff in last Friday (shipped from Japan lol) and had it installed. Car is good as new - no longer leaking any fluid. I've been keeping an eye on the reservoir level since and it hasn't decreased at all. Driving has felt great as well - I'm back to tearing up the backroads like I should be, thank god I'm out of the Passat rental they gave me

Mitsubishi actually requested the dealer send them the old rear diff, as they plan to do an investigation on it. I guess that goes to show how unusual the problem was. All's well that end well.

 

Glad to hear your back up and running, I bet that would be expensive out of warranty, got any numbers?

 

I don't know what the entire service would have costed, but I know the diff alone costs $10,000.