Nick, the '72's were different than the '74's. They only made the clip style window for about a year and a half to two years, and I believe they started in '74 with the clip style. Sorry I can't help you more... dig around in here long enough and deep anough, and somewhere, somebody has rebuilt what you have.
Good luck with it!
-Red, with a very narrow knowledge base...
Somebody ought to clean these windows. There is a tremendous buildup of gook all over them...