For a quick fix to try, I got this small universal overflow tank to try. ($11). It maybe mounted lower than I would have liked, if necessary I will relocate later, The infrared thermometer I have needs a battery so I will check temps later also. Thanks for the comments and help on this topic. I tried to get a new cap but at the parts store , their system only goes back to 1950. Of course the one they showed and didn’t have a rating. I‘ll keep looking.
