Well, I'm not a big "numbers" guy, but if that's an output flange hiding under the plastic bag on the tailshaft it's a '64-'65 transmission for sure.
I'm pretty sure anything pre-'67(?) doesn't have an I.D. pad.
That is like a Candy wrapper with a Big ? on it. Until you open it you'll never know whats inside. I had many frankenstein's come here and The mixed parts would have never worked long at all. I hope who ever put yours together knew what they were doing for the better, and not for deceit.