I purchased this from Bruce Tuley who is a long-time retired telephone lineman from the Central California Coast. This is one heavy duty cast iron insulator pin bracket with a one inch diameter threaded pin and only a 4 inch gap between the pin and three-hole mounting bracket. Much heavier and larger than other one-pin brackets I have observed in many of Lou Hall's pin/bracket displays and on-line photos. It has a number cast in the iron, but I have not been able to find the patent information based on the partial number.

What was it used for?