If you can't find any other numbers, and you want to search inside the piano for clues, have a look at
If you can post photos here to show what the whole piano looks like, or email them to me to post, I may be able to tell you more. There is useful general information about uprights at
Email via my website.
If you find old references or links on this site to pianogen.org, they should refer to pianohistory.info