Whoa....It looks like Ken (KGS above) beat me to it with these same looking units from MEC. I've found a version that looks to be the same piece, only rough cast-not polished, from Honest Charlie's...take your pic from the two links below. DD
https://www.honestcharley.com/produc...se-connectors/
http://modelengineeringco.com/mec.htm
