Found a smaller chain-driven twin screw vise today, and was hoping someone could help me identify the maker. Its jaws are around 4 3/8 inches, it has no post, and one of the jaws has a number 3 in the casting, which would be consistent with a Fisher size-wise, but the style is a little different from other Fisher vises I have seen, and it uses a different, narrower chain. Any thoughts/wisdom?

I believe that this is an earlier model of the Fisher chain vise. Here's an image of an 1875 catalog from a Baltimore tool dealer, showing the dramatically curved outer jaw and the different chain: