With the help of a forum member over at GG, I was able to get the last double ratcheting box wrench I needed to complete a Dunlap set I had going. Dis-assembled and deep clean, ready for work. (The 5/16 has already seen duty removing side battery terminal on the work truck.)
Simple mechanism, really tough, and parts can be made at home if they ever break (which I doubt).
Took me about a year to complete. Total outlay less than $30 I think. I am pleased!

very nice set.  Congrats.

That is a very nice set and I dont think you could buy even an ok set now for that price

Very nice! How old do you think they are?

According to AA, Dunlap stopped making tools for Sears in 1964. So, either they went under, or Sears picked a different manufacturer, or Sears owned them and just stopped having them make their stuff, I don't know.
Here's an internal view of one of the smaller ones to show how simple the guts are and how easy it would be for the backyard mechanic to "manufacture" a part.