See Yamaha FG Serial Numbers, Interior Markings, and Labels – 1966 to 1981 for more information.
Many Yamaha guitars without valid serial numbers have ink stamped date codes on the inside. Japanese dates are based on eras of the reigning emperors (Meiji, Taisho, Showa, Heisei). The first 2 digits of the codes in Yamaha FG guitars are the year based on the SHOWA period, the reign of Emperor Hirohito 1926 – 1989. Year 1 is 1926, therefore the 45th year of his reign is 1970. Then the 2 digit Month. Then the 2 digit Day. Year.Month.Day 45.12.28 equals December 28th, 1970.
Showa 40 = 1965
Showa 41 = 1966
Showa 42 = 1967
Showa 43 = 1968
Showa 44 = 1969
Showa 45 = 1970
Showa 46 = 1971
Showa 47 = 1972
Showa 48 = 1973
Showa 49 = 1974
Showa 50 = 1975
Showa 51 = 1976
Showa 52 = 1977
Showa 53 = 1978
Showa 54 = 1979
Showa 55 = 1980
These are markings on some of my guitars.
1969 FG-230 serial number on neck block.
1969 FG-230 marking on lower bout.
1970 FG-110 serial number on neck block.
1970 FG-110 marking on lower bout. Some of these markings are VERY hard to read and harder to photograph.
1970 FG-110 marking on upper bout.
1974 FG-170 marking on lower bout.
1980 FG-300D serial number on neck block. This was a model not imported into the US. The clear 5 digit serial number so far from the beginning of the FG series is very odd.
1980 FG-300D marking on upper bout.
