My post wasn't addressed to you, RJ, and the second paragraph in my post, regarding Plomb marketing, had nothing to do with the subject of the markings on the Plomb boxes.
The first part of my post was agreeing with Don's recollection of the older discussion we've had on the subject. If you don't understand his point, and my elaboration on it, I will put it more directly.
The Plomb Tool Company changed their branding from "PLOMB" to "PLVMB", on paper and on their products, in 1934 or thereabouts, well before WWII. However, in the late 1930's, in 1940, and in 1941, before our official entry into WWII, Plomb Tool Company boxes of all shapes and sizes were still showing up with the old "PLOMB" logo embossed on them, rather than the newer "PLVMB" logo. The phenomenon occurred before WWII and continued into WWII. Plomb Tool Company boxes eventually started showing up during WWII and continued after WWII with the newer "PLVMB" logo embossed on them. Again, for Don and I, at least, and if I recall, Outlaw and Roy also concurred, it sure looks like they had a **** ton of "PLOMB" embossed boxes made in the early to mid 1930's, and they were using up that old stock in the late 1930's - before the war, and into the war, before they had their suppliers start making them with the "PLVMB" logo sometime during the war.