'78 Saab 99 re-resto in progress - need replacement brake/clutch fluid cap

Hello vSaab community - it's been quite some time since I've posted, but in some ways, this place seems
timeless, so never too late I suppose.

Anyways - as some of you know, I'm the proud owner of two '78 Saab 99's, one that I restored back in 2000
(Anthracite Grey) and one that I purchased in 2005 that had been (mostly) restored and updated (now a
custom/non-stock "Champagne" color).

Well, I'm re-restoring the grey car - it had started to accumulate rust in all the wrong places and have
entrusted the repair and refinishing of this body to a local (central Mass) body man I've developed a great
working relationship with. He's new to Saabs, but he's worked on the champagne car for me and my '84
Mercedes 300SD at very reasonable rates and said he wanted to take on the other 99, so here we are in 2012,
rebuilding a nearly 35 year old vehicle.

So to cut to the chase - the other day I was inspecting the engine bay of the champagne colored car and to my
horror noticed that the brake/clutch fluid reservoir cap had become brittle over the many, many years and
is cracked and useless. This is a very special cap with an integral sensor which connects to the brake
warning lamp. It falls into the category of unobtainium as far as I can tell and am appealing here in case
anyone just happens to have a spare. Will pay any reasonable amount or may have spare parts of my own to trade
that you may want/need...

For now, I'm going to harvest the cap from the grey car to use on the champagne car as I regularly drive this
car, but of course that leaves me still one cap down.

As you can no doubt guess, with the recently commissioned resto, the grey car will need more than just this,
so this will definitely not be my last post. With West of Sweden no longer in business, I'm looking for any
recommendations to a similar source of parts if anyone knows...

thanks in advance and look forward to your replies/suggestions...I may end up using an early 900 fluid
reservoir cap if my trusty mechanic still has any in his part stash - so if anyone know which year/model may
interchange, would appreciate this advice as well.