I think actually that it is I just saw another one with clearer pictures that had this exact same thing on the back of it. So when did they do that? And why? I know in the 70s before they really knew what they were doing they were doing bolt on Les pauls but that was a plate not a single bolt.
Mitch...these were the very last of the Mint Collection. I think they were called "Rock Spirits". They usually had a veneer flame top and the bolt securing the internal join. Never played one myself but I think they were classed as the mid-priced Grecos of the Late 1980's early 90's.
First Greco bolt-ons are from 1990, so Mint Collection. These are the lowest end LP morels, EG-550; chestnut top, basswood back, maho neck. The Rock Spirits are post MC but can also feature a bolt-on neck.