Does this have anything to do with that?

http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&category=53917&item=7956421272&rd=1
It says it's a: Schiebefenster VW-T3 Transporter SELTENES TEIL!!!

bob
gemutlikeits

I bought a drivers side rear slider on German eBay about two years ago
that I STILL haven't got around to installing. I'm leery on pulling
the closet apart as I have rear AC and I can see it being a nightmare
to reassemble. Plus it is tinted and I can't decide to untint it, or
tint the rest of them.

I imagine they still come up for sale from time to time. You can go to
www.ebay.de (note: that is .de not .com), the German word you should
search for is: "Schiebefenster" which means sliding window, of course
you will have to wade through all the middle sliders.

A UK company: http://www.rainbowconversions.co.uk/windows.htm Used to
offer "Volkswagen T3,type25 1979-1990 Rear slider o/s, n/s" windows
for �94.25. But now they just list their windows in sizes, so I don't
know if they still sell them.

Chris