So I stumbled across this old Tune-O-Matic in an old looking original box for a couple of bucks and I jumped on it. After the fact I did a little research and it looks like it's from 1960 or earlier. Reasons: The markings say "Gibson ABR-1" and have the foundry mark, that means it predates 1964, when they changed it to just have the patent number instead. On the side with the intonation adjustment screws, there are no holes for the retaining wire. That was introduced in 1961. The thingys (technical term) that you adjust are metal, not plastic. And they are held in place with an old brittle piece of masking tape since there is no wire and no strings to hold them down. Anyone know if I got all that correct?