I'm using one like the levers in second row of this photo:
View attachment 1435064
I think that's a Folmer variant, as the pins are in the same location as the rusted pins -- and there seem to be far more smooth-pinned flashes out there than levers with the rusted pins, so looking at this a variant would explain that shortfall. I also think that explains why the pin looks especially large in some of the ANH prop photos if you compare it to an Inc -- it's not necessarily a size issue, but placement. I think that for the Incs, in the third row, the pin was reposition to make the lever stronger.
(I've gotten this style clamp on Folmers flashes both with and without patent, so I don't think it's diagnostic to that end.)