Maybe I need to research further, but the web sites I've read so far only identify the postcard back I posted as no older than 1950 - but I've found nothing that tells me that it's not post-1960, or a reproduction.

As far as faking such an item, I was under the impression that RPPCs were re-issued from time to time, and also that ballplayers had copies made for autographing purposes (I know Killebrew signed a bunch of modern reproductions of 1960s team issue photos of himself, and he also signed a bunch of RPPCs just before he died that were auctioned off by his estate - so I wonder whether those could be reproductions also).