Identifying Vintage Gibson Electic Guitars can be a little tricky at times. Relying on the serial number is not always the best way so using a combination of serial numbers, factory order numbers and design features gives the best result.
Factory order Numbers (FON’s) were used by Gibson to track batches of instruments in the early days when they made guitars normally in batches of forty. Therefore early Gibson Vintage Guitars may have both a FON and a serial number. The FON will even provide what number in the batch of forty guitars your instrument was. The FON is the only identification number on Gibson’s lower grade models like the ES-125, ES-140 etc.) which do not feature a paper label. High grade models (such as the Super 400, L-5 etc.) have both a serial number and a FON.
When both numbers are present on a high grade model, please remember that the FON was assigned at the beginning of the production run, while the serial number was recorded later (before shipping).
The serial number would be the best indication of the actual date of your Vintage Gibson electric guitar.