Hi Grunther -
I just scored a NOS Carburetor Idle Stop Solenoid GM part number 199746 off eBay. It appears to be the correct one, at least from the photos. With my Amex eBay $30 credit they are running until June, only ~20 bucks. Between shipping to you and back, seems like its a worthwhile try (Seller has been around since 2000 and has high reviews).
I did finally take my off, it appears to been hit or something, the top is a bit busted. Also the plunger is not moving very well and I assume at rest (no power) it should spring back - which it doesn't. So I am not sure it is worth working on.
I tried to get the darn thing opened but I haven't anything to help release the indentions.
Assuming all is well with my "NOS GM 199746" I'm likely to use it to speed up the idle when the AC kicks in
