You and me both![emoji481]
Well, Todd, when the "later research" is concluded (or you think it can be done with photographs of your
former wrenches...

), I am calling first dibs on the wrenches if they're different size openings than the ones I've got!
The PA reference is strange, since the label says Camden, NJ, and Randolph is a small 'burb just outside of Camden, but this is a great point, since the area makes perfect sense for Signal Corps. Camden (historical home of RCA and all kinds of lesser radio accessory industry leaders) is on the other side of the river from Philly, where the Signal Corps was centered during the war. EJ McAleer, which made their toolboxes, was in Philly, as was Fleck Brothers, who put all their big tool-sets together. And, Philly was the home of Sears and Roebuck, who was a huge supplier to the Signal Corps.
Confirming Signal Corps, as well as my suspicions that R.T.E.C. was an integrator, here is a friend's Craftsman (BE) midget set inside a box with the same label...
It came with this steel rule, sporting the Signal Corps logo...
Note that this box - filled with New Britain tools - is the same exact box, no Randolph label...
...which might mean it was also put together by R.T.E.C., or New Britain used the same box supplier.
Either way, I am starting to think R.T.E.C. may not have been an OEM at all.
Note that the 64ths had automotive functions as well (e.g., inside distributors, generators, magdynos, etc). Every motor vehicle mechanics' tool-set had an ignition set with 13/64 (15*) x 15/64 (60*) and vice versa in them. Duro ("E" and "G" series) made a ton of them. Others, too. See upthread.