I ran across this while surfing "the bay" (no affiliation)

http://cgi.ebay.com/ebaymotors/BMW-5...QQcmdZViewItem

Would make a good start for a 5-spd conversion or replacement trans or engine block. Should be the same Getrag 260/6 that's in an e34 535i. ETK shows the 260/6 5-spd from 09/85 on up.

Downside is the seller won't ship.