Old Snap On double detent drives

[Provincial]

I have a couple of 1/2" drive Snap On handles with an extra set of detent balls higher on the square. The square section is extra long in order to accomodate this. Any idea how old and what the mating sockets look like?

 

[tool-nut]

They are likely stops for the socket and are not spring loaded. They would have fit regular sockets. Pictures would help date them, but probably 1920-30.