Sorry for the delay..with work and other guitar projects!
To get the pics I just stuck my cell phone into the sound hole as shown in this video:youtu.be/sg Qr MQKo4z EI tried to direct other viewers to your forum to add serial numbers to your list!
Since there seem to be models that have both types of numbers, I'm wondering if there where 2 plants that each had their own numbering systems. I’ve been collecting data on vintage Yamaha FG acoustic guitars for a few years.
I'm repeating a post I've made in a couple other forums. This past May Yamaha deleted their Yamaha Guitar Archive web page, pushing me to start a forum to share the info that I’ve collected, including all the data from the Yamaha Guitar Archive.
On You Tube I found a guy in Japan who’s posted short videos of many vintage FG guitars, with the year, model number, partial serial numbers, and in a most cases the internal date code.