A good question. I have had a few WF ratchets without any name or part number except the O. On one or two the Plomb name was stamped in the bottom plate. My theory is it was contract work and so the ID marks were not important.
But then Plomb seems to have been very inconsistent on details between production runs. The selector switchon ratchets sometimes points towards the handle and sometimes towards the drive lug and sometimes the switch works clockwise to go reverse direction and sometimes counter clockwise. With the pebble ratchets the fields and lettering differ quite a bit. Perhaps there is a pattern but it sure is beyond me what it is.
