Greetings:
If you want a Porsche tranny, my suggestion would be to check out some of the Porsche sites. There are some 
good deals available even with the Porsche name. A year ago I purchased a good aluminum 915 unit for $ 650 US. 
Make sure you do some research/homework and make sure you know the right questions to ask and also how to 
identify the years, model, and gear ratios. 
Here is an excellent site to start from and you need to "watch" daily otherwise the deals are gone quickly. 
Link: 
http://forums.pelicanparts.com/forum...php?forumid=17
Link: 
http://www.rennlist.com/ads/
"sonjay" is the login for a company in Florida and they are very good; also 
since they build race cars also seems to get a fair amount of parts cars !
(also try #407-497-9944 ask for Jason)
Trust this might help you our and get you on the right track in running
a 915 tranny in VW. (Make sure you arrange to have the ring gear "flipped"
to get 5 gears forward !)  
Allan