Found it in a barn sale today. Big sucker. 5/8" drive. Four and three quarters inches long.
U-joint is A 10; the socket is A 19. It looks to be 15/16".
There is no friction ball on it. Instead, there is a riveted clip inside the female end of the U-joint.
No rat or other components. Dang it.
http://alloy-artifacts.org/chicago-mfg-company.html