There is an relatively easy replacement for lost or broken screw/box for old leg vises. I Have done this on several vises that I found without the screw/box.
When leg vises were being made and sold there were probably only a few manufacturers of the screws. They also supplied similar screws for other purposes.
During that same period a lot of screw type railroad and house jacks were made and sold. These types of jacks used high quality steel for the screw and cast iron for the female receiver