First generation: 1966 to 1974, Green & Red labels, Nippon Gakki & Taiwan. The original FG’s, introduced between 1966 and 1968. FG-150 & FG-180 (1966). FG-110 (1967). FG-75, FG-140, FG-230 & FG-300 (1968). High-end (hand built) FG-500 & FG-550 (1969). And other high-end (hand built) models introduced in 1971. Only the FG-150 & FG-180 where made with Green labels from late 1966 to early 1967. Red labels started in early 1967. Taiwan Red labels started in mid-1971.
The FG-75 & FG-110 continued to be made in Taiwan until mid-1975 (Tan label starting in late 1972). The FG-75, FG-150 & FG-300 continued to be made in Japan (non-export) thru 1974 (Tan label starting in mid-1974).
Second generation: 1972 to 1975, Tan labels, Nippon Gakki & Taiwan. Additional models introduced – FG-45, FG-160, FG-170 & FG-200. Some previous models were obsoleted. Some new models introduced in Japan are exclusive to Japan (non-export).
Third generation: 1974 to 1977, Black label, Nippon Gakki & Taiwan. A revamping of some previous models (and added “-1”) and a few new models. FG-75-1, FG-110-1, FG-160-1, FG-180-1, FG-210-1 & FG-260. Japan changed to the Black label models in mid-1974, Taiwan in mid-1975. Japans new models are exclusive to Japan (non-export).
Fourth generation: Taiwan White oval label, early 1977 and up. Nippon Gakki Orange oval label, late 1975 and up. All new models. All previous models are obsolete. Taiwan models – FG-312, FG-325, FG-330, FG-331, FG-335, FG-336SB, FG-340, FG-345, FG-350W, FG-351SB, FG-365S, FG-375S, FG-412SB, FG-512, FG-750S & FG-770S. Once again, Japan changed to new models before Taiwan. Japans new models are exclusive to Japan (non-export).
There is some overlap of models between the First and Second generations because a few First Generation models continued to be made in Japan and Taiwan.
Model numbers listed for each generation are common export models.
I’ve excluded some models in Yamaha’s archive that I don’t have any serial numbers for and have never seen.
I only included “vintage” (before 1981) Fourth generation models.