I tried to get a set for my 66' Coronet a couple years ago and was told there was no such thing

I finally found a Carquest that had someone who knew what I was talking about. He said that it was a thing of the past as they are made to "exacting" standards and are all the same. I protested but he insisted all would be well. So I ordered them and they wouldn't work. One was flopping around really bad and the other nice and tight They took them back and I found myself at a Advanced Auto parts next. He ordered in like 5 or 6 of them and I picked the two that measured up similar on the belt measurer they had.

Not perfect but close. Haven't had any issues with them.

Sad thing is not 10 years ago was able to get them no problem for my 69' (matched set)

Good luck on your search