female/female universal

[rust in the eye]

Its been suggested that this would have been used with female drive ratchets but those I've seen were hex drive.
This seems the place to ask what/how it was used.

 

[yatg]

********* with two male drive ratchets.

 

[MShaw]

To access square head block drain plugs on older engines?

 

[3baygarage]

Brands like New Britain and Duro certainly had square female unjoints like that.

 

[four.cycle]

Indestro (and most likely Duro) DID manufacture a 1/2" female square drive X 1/2" female square drive universal joint:

Indestro 3214 1/2" female drive universal joint 1935 Indestro catalog pp 11

Not sure about New Britain - I didn't check.
The nice chrome plating on your specimen suggests later vintage.
There were lots of European manufacturers of female drive tools. (A few Russian ones as well.)

 

[humber2]

Who made this male/male 1/2 drive u/j I got this weekend?

Every surface has been machined, the swivel pins are plated over.

No idents to be found, perhaps the inserts over the ball holes are an identifier?