I have managed to solve this problem with the help of Michael Berger webmaster of TYP15.com the international registry for VW Beetle convertibles. As I suspected, my window frame was actually from a 1975-79 Beetle even though it came out of a 1973. The oval glass which I purchased on E-bay is 28.5 cm X 79.5 cm, the correct size for 1963-1974. One VW convertible specialty supplier in the USA, who shall go nameless,
knew the answer to my question but wanted me to supply a photo of my frame and they would supply the glass for a paltry $ 195 plus taxes, shipping etc. As a result, they will get neither the order for the glass, which would have been wrong for my year of car, nor will they get any other orders from me. So nyah, nyah, nyah on them! Keep the faith VW owners. There are still people out there like Michael Berger who are in it for the love of the cars. Dan ( MY72BUG) in Goderich, Ont.
I'd rather have a partial bottle in front of me than a partial frontal lobotomy.