Was at a garage sale for lunch and they had a Disston saw looked like maybe a D8 because of the bolt pattern. One of the nuts on the flat side had a extruded letter S on it? It was brass nut (not split). Lady said it was from the 1800's. The saw was in real bad condition, couldn't see any etching on the blade. Didn't have a camera. Has anyone seen a S on the nut before?