I recall the time period (70s but not 60s). I never personally saw any vestment burning, but I do remember seeing the “fiddleback” vestments hidden away in remote places like church basements (when I went wandering and exploring in places I really should not have been to see if there really were black vestments hidden in the “dungeons” beneath our Gothic parish-church). I also remember (distinctly because my parish had only one set of vestments in identical plain polyester, one for each color) the plain vestments of the 70s.
Burning old vestments is actually the proper way to dispose of them, rather than putting them in the trash. There might be some anecdotal stories of parish priests in the 60s gleefully burning all those “pre-council” vestments in bonfires resembling some combination of a druidic human sacrifice and a drunken fraternity toga party—but I suspect these are more apocryphal than they are representative of the era. At least, I was never invited.
Ah memory lane … I remember the late '60s, and the stories aren’t exactly anecdotal. While I wasn’t exactly “invited” to the fire-fest, I did see some of those pyres. Yes, of course burning is the proper way to dispose of old, threadbare vestments, but what I saw burned were relatively new sets.

(I’ll spare the details of where this occurred, lest it shock some readers.) Other vestments weren’t even burned: they went right out with the weekly trash pickup.

And the first to go were always the black sets and the rose sets.
But yes, it was kind of like a combo druidic-fratboy toga party thing. The principles (mainly clergy and religious sisters) with the torches were thrilled to be doing an “out with the old, in with the new” deed. And, oh, the “replacement” sets.

Charming piles of felt and even burlap.

What I find funny is that many of them weighed a ton and were hotter than blazes to wear! That didn’t deter the wearers, though. The more hideous, the happier they seemed to be. :banghead:
The point, though, (again, back to the OP) is that there is simply no such thing as pre-Vatican II vestments and post-Vatican II vestments. Even though that distinction was not explicitly made, the question OF vs EF in the question makes it plain enough.
All too often, I hear people, indeed even priests who really ought to know better, speaking as if there are 2 different forms of vestments, pre-Council and post-Council. It’s all nonsense. People who say they want to go “back to the traditional form” just don’t know what they’re talking about, and neither do those who try to reject some forms as belonging to those who don’t accept Vatican II.
All true, of course, but the practical elimination of the “old” to be supplanted by the “new” was so obvious that it was really only the clergy who knew better, and even then, so very many couldn’t have cared less. Even they bought into the bogus "spirit of Vatican II’ stuff. Far too many still do.
