I have two Kay archtops from this era, and they both have this kind of tailpiece, so I'm going with Kay. These were sold by the gazillions through catalogs, as we know, and they were built like Mack trucks, so they lasted through all sorts of abuse and neglect. BTW, on one of mine, I hand-sanded all the finish off and then rubbed it with gun oil- it look spectacular, and even sound pretty good.