Yes Sir they did. Believe there are a whole series of4 digit numbers in the 4 line time period. It was sometime in that period they dropped a digit or 2 . By the short line period (1946 to 50,51) they went to 2 digit. IIRC. Vit knows a lot more of the details and maybe he will chime in .
The 4 digit ones are very early 4 line stamped knives . Can’t remember the 3 digit stuff .
Take care out there.