Jeff, why not just make one out of copper tubing and a heater system bleeder.
 Wouldn't take a experienced plumber more than a few minutes to put together
and would be way more sturdy than a used unit out of plastic.  For those who
think it would be terrible to put a piece of copper in the Vanagon cooling
system, I would like to point out that many Vanagons had copper core
radiators.  I wouldn't think a little piece of copper would hurt anything if
you could have a whole radiator made of the stuff in the system.

Thanks,
Ken Wilford
http://www.vanagain.com
John 3:16

New Phone (856)-327-4936
Shop: (856)-765-1583
Fax:     (856)-327-2242