First, a little background on Bridges compliments of Stew mac
A Tune-o-maticbridge timeline:
1954: ABR-1 bridge-wired
The ABR-1 is the original Tune-o-matic, designed by Gibson’s Ted McCarty for their arch-top guitars. Its first Les Paul appearance was on the Custom model in 1954. It’s a slim bridge that sits on two posts screwed directly into the maple top of a Les Paul. At their Kalamazoo factory, Gibson used this bridge for over two decades.
1977: Nashville bridge
The Nashville Tune-o-matic was introduced after Gibson moved from Kalamazoo to Nashville in the ’70s. It offers a wider range of saddle adjustment than the ABR-1, which is great for intonation. This bridge is a fair bit larger than the ABR-1, and its support posts screw into metal bushings pressed into the guitar top.