Hate to admit this, but I had one do the same. I drained it so as to not leak for the moment, cleaned the heck out of it so no residue on the outside, then used our old friend FB followed with some rattle can paint. That was on the SWB a good seven years ago. Granted it hasn't seen much road time, but it has held up fine so far. I went this route at the time thinking I'd get an MS locker at some point...

Big Truck: 00, 3.5, Endeavor, 5-Spd drive line in hand!
Little Truck: 87, 2.6T I/C, MT, LSDs, Tonneau Top
Her Truck: 03, 3.8, 20th Anniv, 65k
Daughter's: 06 Eclipse, Keeping it Mitsu!
FSMs: MitsubishiLinks.com