FG labels
The final three numbers are the unit number; 123. This model made it at least through 1979, and possibly a year or two more. Six numbers, like so: 610101. The second letter is the month; June.
Sponsored Content is clearly labeled everywhere it appears, and Premier Guitar's editorial department has no involvement in its creation. He had custom pickups without the covers, and a fancy pearl inlay design covering the belly of the guitar. The white labels can be found as Nippon Gakki: Made in Taiwan: and with none of both: Also somewhere around 1972 while starting making guitars in Taiwan the red label lost the Nippon Gakki: After that the black label was introduced. The first number is the year; 1998.
Yamaha SG1000 - These had slightly less fancy headstock inlays and chrome hardware. Kaohsiung Factory, Made in Taiwan, 2001-: Letter-letter-letter-.