I believe I purchased a vacuum control valve from slantsixdan awhile back (NOS and its green). I have two '65 A bodies and a '72 B body. Not sure yet which vehicle I will try it on.
My stock 67 dart 273 2bbl (So Cal car) has one. I believe it to be the OE part as the carb tip is metal vs the 4-5 on ebay that are plastic and it still functions (dad wasn't one to change a part unless it was shot). it has a green spring and the active coil count is the same. there is an adjusting screw on the back to reduce the tension on the spring I suspect that way it can come in at a lower manifold vacuum.
With CAP for 67 273 2bbl initial timing was 5 ATC, without CAP it was 5-10 BTC (manual - Automatic) the dist mechanical advance curve was also difference between CAP and non CAP
Oh the fun of early smog controles. Who remembers smog pumps?
This link from inside the link posted by dibbons has a great full color booklet covering the valve. On each page there is a link on the bottom that has a huge PDF that you can save and/or reprint, unfortunately you have to save it page by page.