Yamaha Nippon Gakki?
 

I got this guitar from a friend. A really old, really beat up classical guitar. It was missing a tuning peg and the bridge saddle, the nut was gone and it had no strings. The neck was split where it meets the body. And it was dirty. Very dirty. I fixed all of that, put some steel strings on it and now I just carry it around in my car since I got it pretty much free.

Anyway, on the inside it had a little square sticker (looks more like a piece of paper that was glued in) that says Nippon Gakki Yamaha Dynamic Guitar PAT NO. 187409 N. S70

So, it's clear to me that it's very old. Are they, by any chance, worth anything? I highly doubt it, especially in the condition it's in, but a man can dream. I can't find this particular model on the internet anywhere, so I had hoped they were rare.

I took it into my local store and the guy didn't really think it was anything special. I simply hoped he didn't know what he was looking at.

Anyone know a little bit about this thing?

dynamics are supposed to be pretty good, probably not worth a whole lot but probably worth fixing up and playing

I would recommend removing the steel strings before the guitar is damaged. That is a nylon-string guitar.
It may hold up for a while, as it's likely of laminate construction, but steel strings have twice the tension of nylon.
You might find your bridge lying on the floor....

This.

I've thought about it. But it's mainly just for practice. I figure I'll build callouses quicker with steel strings than nylon.

I got it for next to free, so no big deal if it breaks. Unless it's worth something.

Well until you find out if it's worth anything, put nylons on that thing..

And then Google the crap out of it :P

Trust me, I searched every possible way I would think to search. I couldn't find jack. Which is very frustrating.

I did some research on these old Yamaha's and the Dynamic series, if I'm to believe what I've read, these Dynamics were made in the late 1950's. They were believed to be outsourced by Yamaha to some very fine craftsman from another company in Japan and apparently made a fantastic product. I think yours has a laminate top because of the S before the model number but should still sound great. There aren't that many left because they are so old. I believe these Dynamics could be used with either steel or nylon strings but owners have said nylon sounds the best and will put less strain on the old neck anyway. If it can be made playable, it should be a keeper.

I have one I got for $95 at a thrift store auction...Yamaha Dynamic Guitar ..Patent#187409 Model S-70....when I got it ,my Gibsons ( 1947-51 Archtop - !969 LG & 1961 Les Paul Electric ) hung on the wall for a couple of months before I played them again. This little guitar has a voice that equals any Martin parlour guitar I've ever heard. It is a misconception that these were for nylon strings only...this one had steel when I got it 2 yrs ago & still does.Robert Johnson would've loved this babe.I use it for a slide guitar.My eyes say the top is solid spruce as I clearly have end grain showing at the hole...if it's laminated , they made it nearly invisible...back & sides are laminate...Nippon-Gaki label puts it anywhere from 1957 to 1965...money ? Mine isn't mint..needs new tuning pegs knobs but machine heads are rock solid in tune...it was well used before me.....they are worth as much as someone who loves the sound as much as I do will pay for it's sound...My Gibson Arch top has $1100 into it and is a beauty but I play the Dynamic more often

I'm with Bikewer , get the steel strings off before its rooted, Cheers