I don't think it has been fully understood. I don't think it is a date code as the letters range from A-E giving 5 examples. It possibly could be a plant location of manufacturing, production line number, or even a fordging die number.I got PLOMB Combination Wrench 1230 Los Angeles "4C".
I know that "4" means product year 1934.
Let me know the meaning of "C".
Question from Japanese collector.
I don't think it is a date code as the letters range from A-E giving 5 examples. It possibly could be a plant location of manufacturing, production line number, or even a fordging die number.

As I have noted before, akin to the letters we sometimes see on some WF- series tools, in my opinion. More letters, because it was later production (i.e., more plants, lines, etc.) And, also as I have noted before, like those WF- letters, I don't think this code can be cracked empirically, through examples and inference. We're going to need documentation on this case.
As I have noted before, akin to the letters we sometimes see on some WF- series tools, in my opinion. More letters, because it was later production (i.e., more plants, lines, etc.) And, also as I have noted before, like those WF- letters, I don't think this code can be cracked empirically, through examples and inference. We're going to need documentation on this case.
I agree. I know the WF swivels have all sorts of letters up to K is the highest I have seen. It would be good to do a research project on this hypothesis.