I tried a female 1/8" pipe thread fitting on the vacuum port of the Carter YF. It went on, and made about 1/4 turn before the threads bound up. So, the size seems right, but the threads are different.

I spent time this afternoon at different auto parts and hardware stores trying to find something that works. I didn't expect this to be difficult.

-Kevin

This is what happens when you live with a house-full of women, the wife and daughters name all the cars:
1960 Impala - "Frankie" (Frank Sinatra)
1961 Apache - " 'Mater Jr." (wrecker)
1965 Corvair Monza Convertible
1967 C20 "Ol' Blue" (hidden in a log cabin for 30 years)
1972 SuperBeetle Convertible - "Juliet"
1976 SuperBeetle Convertible - "Olaf"
1988 Alfa Romeo Spider Veloce - "Romeo"