I don't think this is the coupler that Tim is talking about. It's one of the pre-magnetic ones I think. It had a slot in the back and a spring was attached that applied the springing action. The spring was behind the center pivot post. I'm pretty sure this was one of the first Kadees made.
Yes, this is the coupler that I am talking about; and yes, it is also a seamless continuation of an original pre-magnetic Kadee coupler shank design.
As an aside, I would suspect that this design has now been produced unchanged for at least 55 or more years, surely a millennium in model railroad hobby terms!
