A friends “64” was loved and cherished by him for years, then he found out it was actually a 63. Probably done when the 63 was a year old and the new 64 had a one piece rear window. The split was removed, new one piece rear screen installed hey presto your in the money.
It’s been put back to a SWC now ( many years ago) so he’s in the money.
By all accounts it was quite a common conversion.