bloody hammer

I too have a Yamaha FG-335 from the late 70's. I bought it back in high school and have loved it ever since. I have dragged it through all kinds of situations (good times/bad times). It may be beat up looking but it sounds just as good as ever... even better! So, now all these years later I'm starting to take stock of what I have and look back on things. Many years ago I was goofy enough to put a sticker inside the guitar... right on top of the label. I guess I thought it would look cool or something. At some point I tore off the sticker and unfortunately some of the label came off with it. That didn't really bother me at the time but now I wish I was able to read the label a little better. It's definitely a FG-335 but what I can't see is the serial number., Also, does anyone know what the "MN" stamp on the right side of label stands for? I've searched on-line for photos of these FG-335 labels and of the few I could find that area of the label was just a blank line. Any ideas?