Before today I've removed the necks (and 15th fret) from (5) vintage Yamaha FG's: 1973 FG-200 1973 FG-160 1974 FG-170 1971 FG-180 1973 FG-110E
All are early 70's. The first (3) made in Taiwan, The last (2) made in Japan.
Today I removed the 15th fret from a 1969 FG-230 (Red label Nippon Gakki), in preparation for a neck reset next month. I found the fret is different than the ones from the previous (5)!! The tang is much thicker, the crown height is slightly lower, and the features on the sides of the frets are different.
Are all 60's FG frets like the FG-230?? The only other 60's FG I have is a 1967 FG-150. It's in line for a neck reset, eventually.