Pitching in.
I have infuriatingly few pics with legible switch codes in my archive, for some reason I've never really thought about them before. Looks like which side I've shot the switches from has been largely dependent on which direction the pickguard wanted to flip when I took it out...
Anyway, here are five of them. I've correlated them with neck/body codes, might be a good idea if we suspect that there is a month code involved. Which I definitely believe the second digit is, as a D for December turned up in one of these.
Re. the third digit: so far, 1, 2 and 3 have been seen. This lines up with some of the older pot codes (not used in Tokais, as far as I know), ending either in 1, 2 or 3 or with 1, 2 or 3 vertical lines. It has been suspected to denote the
jun, i e the third of the month the part was manufactured, according to traditional Japanese reckoning. I don't know if this is possible to confirm other than through official sources or eyewitness accounts, but on the other hand it's more of a curiosity than a meaningful dating tool...
TST-60, 1983: switch 341, body 5=1
TST-60OWR 1983: switch 391 body 10=1
ST-50BB 1982: switch (probably) 193, body 10=5
ST-50BB 1982: switch 1D1, body 3=2
An finally, a all-Tokai parts guitar I put together a few years ago: switch 103