I have the same guitar only it is marked 552 inside. It is really fascinating to meet someone with the same guitar that is 554. I am 38 years of age and the guitar was my father’s guitar. He bought it in 1971 but never learned to play it. Then in 1984 he gave it to my brother and me to learn to play. 26 years later we are still playing it and I went on to get a degree in music from Berklee College of Music. The guitar was probably made within the mid 60s and my Dad bought his in ’71.

I just read your post on the Sylvia 554 you have. I also have one that I found in my dads storage after he passed. I had some minor repairs done and was told it was called a Parlor Guirar, I was also told it was called a Classical Guitar. It plays very well and has a good tone. My Mom said she recalls seeing it during the mid 60’s. No further info. Did you ever find additional info on it?