These are some sketches I did a while back after having the insulators cut in half. It should help when trying to identify a manufacturer. Enjoy. ONe oof the tricks I use to tell the difference between the Oakman threads and the American threads is that the Oakman threads have two, small double circles opposite of each other at the top of the pinhole. These circles are the hinge part of the collapsible pin plunger used by Samuel Oakman. So when I see these "O"s I think "O" for Oakman. "O" how unAmerican this is. LOL