Hi,
I have an M.Suzuki W-544 12 string which I purchased in Darwin, Australia in the early 80's.

Looking inside the sound hole to the base of the neck, I see the letter "N" and underneath that the serial # "807161".
It's possible that the first 3 numbers are the year and month of manufacture, ie, July 1980.   That's only speculation of course.

It's still in very good condition, sounds nice, has never been back to a guitar shop for adjustment, and the strings are probably 25 years old, well only 6 of them, you know what I mean.

http://s1081.photobucket.com/albums/j358/v8sruleok/Guitar%20album/