I have a question about the 1966 C-code PCV's. The MCA Rule 4.T. states: "64 1/2-66 all models with PCV, hex base design." I did a search on this forum and found out that the finish should be silver zinc. So I know that it should have a hex base and a silver zinc finish. On my engine, the PCV pushes into the valve cover grommet and also into the hose from the back of the carburetor. Where there any PCV's that screwed into either the valve cover or the carb? I have seen a few for sale and I was wondering if the screw-in could be correct or is the push-on correct? Obviously my question relates to Concours correct applications only and not aftermarket or service parts.