I don't know if this applies to the mid 60s a bodies as I can't recall a specific car, but I remember some of the owner's manuals having the Certicard in them. I also can't recollect how it was affixed to the manual. There may have been a page with slots that the corners of the card went into. I also seem to recall some taped into the owner's manual but maybe this was done at the selling dealer.
As always I love this thread, not only for the fantastic restoration but also for the stories about how things were done back then. And I'm continually amazed at the knowledge some have to share. :thumbup::thumbup: