The Masterbilt serialnumber system did not start with the number 1000 but with the number 5000. The serial numbers were blind stamped on the interior back under the bass f-hole, generally below but sometimes on the (oval) label, maybe even without a label like the earlier Recording and Seville models.From about 1934 forward, the serial numbers were ink typed directly on the label (Long Island label) or letter pressed on the label (rectangular Masterbilt label, Green label and Blue label).The sixth number represents the location where the instrument was made, and the last two digits show the "production run" number.
The only difference is the addition of this batch indicator.
NOTE - Gibson USA goes to a 9 digit serial number in early July 2005..
The sixth number is now a batch number- batch 0 starts at the beginning of the day, and once we stamp 699, the batch number will change to 1.
ELECTRIC GUITARS “While Epiphone’s SN systems for acoustic instruments and 1950s electric hollow bodies appear to be pretty straightforward, the SN systems of their other electric instruments and amps are much less so.
Over the years a number of different SN systems were used.” (Wiedler) “With the inception of the Electar line in late 1935, Epiphone began a new numbering system which was employed solely on the electric instruments (Electar, Century, Coronet, Zephyr, Kent, Harry Volpe model).