Help - Where can I get an '88 Torsen diff?

[Avram Dorfman <dorfman@est.org>]

Does anybody know where I can get a replacement Torsen diff for an '88
80q? Just the actual diff to put into a tranny that we're rebuilding.

Which cars is it the same as? Is there any way to get a used one w/out
buying the whole tranny?

The Audi dealer told us a new would be "over $2,000." Can anyone confirm
or deny this?

Barring any of these solutions, does anybody have a used tranny for this
car that they are getting rid of for a reasonable price?

-Avram