Unknown Stamp on Shin-Gunto's Tang

So, I am currently trying to find a likely age bracket for the production of my Japanese Shin-Gunto Sword. Based off the sheath, handle and hand guard (Tsuba I think its called) I assume it is from late ww2. To get a more accurate estimate, I decided to take the sword to pieces to see if there are any serial numbers, arsenal stamps or a name on the tang as there are none anywhere else. After a bit of struggling to take the sword to bits due to the whole thing being rusted together I found that the only thing on the tang is either a 10 or a sideways IO, and I cannot find anything on this online so any help is appreciated.

 

You may be aware of these pages already:

http://www.japaneseswordindex.com/realold.htm

http://www.japaneseswordindex.com/military.htm

 

nice blade....
she should be cleaned and oiled..

 

Thank you for recommending this website. I have used this site previously to figure out that my sword is from late ww2 but from what I can remember it had nothing about my markings, then again I may have missed them so I will have another look.

 

I think that it is simply an assembly number. Usually these are painted on the tang (nakago) in red, white or black paint, but I have had a couple with the number stamped in. It is also a slightly odd place for it, usually when painted they are in the middle, or those that I have had with them stamped in are at the bottom, but sideways like yours.

It is either extremely late war, or possibly put together just post war to sell to the GI's as souvenir.