4kq rear differential

["egav@rogerswave.ca" <efraim@rogerswave.ca>]

I would like to install some kind of limited slip device (torsen, 
quife, etc) in the rear differential of my 4000 quattro.  Is there a 
supplier or an individual who knows were it is possible to obtain 
such an item.  While on the subject of my car I am curious if a rear 
calper from a 200 20v quattro would fit the strut on my 4000 quattro. 
 The reason is that I want to upgrade to vented rear discs and still 
retain my hand brake.  Maybe there is a better solution.