Wanted to see what everyone else thinks about this. Trying to decipher FON/Serial number system for post-war Gibson es-125.
I just picked this one up, and I suspect it's between 1946-1949, but I'd like some opinions to help narrow it down further. The back of the headstock has the engraving 4G642 (followed by a rough gouge, not sure if it's supposed to be a 1, or if it was something else carved by a previous owner). The guitar has trapezoid inlays and raised diamond trapeze tailpiece. I haven't seen any photos online of other early es-125 guitars with engraved FON/serial numbers like this on the headstock.
Appreciate any insight y'all might have.
Thanks!
Chris