This might help in finding one - from Bus Depot site.

Fits Vehicles:

EuroVan 1997–2000
Vanagon

2.1 Liter 1986–1991
Air Cooled 1980–1983
Diesel 1981–1984
Syncro 1986–1991
--- On Fri, 9/28/12, John Reynolds <transporterjr@yahoo.com> wrote:

From: John Reynolds <transporterjr@yahoo.com>
Subject: Re: Brake reservoir needed in ri
To: vanagon@gerry.vanagon.com
Cc: phishman068@GMAIL.COM
Date: Friday, September 28, 2012, 12:43 PM

Craig,I'm in Middletown, RI.  I know where one may be. I'll p-mail you my contact info.John R