Why can't I find out how much this diff is worth?

I have an '80 635 CSi Euro that I'm parting out. I've looked all over the place, and all I can find is diffs that load the carrier from the rear. Mine loads from the side, and I can't find anything telling me of the value.


I've got a pic in my gallery at http://files.automotiveforums.com/gallery/showphoto.php?photo=36802&password=&sort=1&cat=500&page=1


Thanks for any help you could give me!
cale