What's it worth?
Here's a picture to put the car into perspective
I would see if you can get a hold of a used 3-series carrier (93-02. 99-02 use a Torsen style, I like it more, I have it). Either with, or with out gears. If w/o I have 3.23s I'd sell you for $20 (+ship) with only 95K on the ring and pinion.
If you're technical enough, you can install it then cheap (probably re-use bearings wouldn't hurt much since selling).
Otherwise with paint (assuming it matches nice), I'd say you might now get $2,500~


