Where to find the serial number The serial number is stamped or punched on the back of the headstock.Factory Order Numbers (FON) with a letter from 1935 to 1941.Gibson stopped the stamped serial numbers at the end in 1960, although there are a few guitars made in 1961 with a "1" as a prefix.
FON consists a batch number of usually four digits, followed by a one letter (sometimes prefixed by a space) followed by one or two digits (ranking).1935-1937: Letter between the batch number and the order number. 0123 A5 1938-1941: Two or three letters before batch number. If there is a second character follows it is the code for the type of the instrument.The electrical models were provided with a rectangular with black and purple triangle.It was also from 1970 "MADE IN USA" stamped on the back of the headstock.Some instruments from the fifties also had been such a stamp. At serialization in the 70s a random method was used.
Guitars got six digits in any order, and in some cases they were preceded by a letter that none seemed to have no smeaningful sense.The three intermediate digits, the day of that year. After opening of the new factory in Nashville, in the sequence numbers were also included the production site.001 to 499 appeared on the instruments built in Kalamazoo, 500 to 999 built in Nashville.From 1902 to 1976, Gibson instruments have a serial number or a FON (Factory Order Number) or both.However, in the beginning this was not done consistently, so that there are also be instruments without identification.(G = Gibson, K = Kalamazoo, W = Recording King (Montgomery Wards).