After the FG series guitar manufacturing moved to Taiwan in 1971, guitars continued to be made in Japan for sale in the Japanese market, including many new models and duplicating a few of the models made in Taiwan.
These guitars have 5 digit serial numbers, in the format YMMDD.
From 1973 to 1976 they have rectangular tan labels that say Nippon Gakki. In 1977 they changed to an oval orange label, while the Taiwan models changed to a white oval label.
See Yamaha FG Serial Numbers, Interior Markings, and Labels – 1966 to 1981