Thanks to all who have been helping me identify these odd vintage
transistors. I have another one here. It is a TO-18 and is gold all around
(plated, I assume). Although that is a curiousity to me in itself the real
oddity is that it only has two leads protruding from the underside. The
third lead is in fact attached to the top of the case and sticking upward
(collector?). I can't help but wonder what a typical application for this
would be. Since resistors and ceramic condensers are thinner than the
height of a TO-18, could the transistors have possibly been mounted on a PWB
with their leads sticking upward, and a second PWB mounted on top, through
the leads of the transistors, like a sandwich? I'll try to draw in ASCII
(fixed-width font) what I'm envisioning here. As suggested earlier, I
copied out of Notepad.

| | Transistor top leads sticking through
===================== "Top" PWB
_| | _| | TO-18 transistors and other components
===================== "Bottom" PWB
| | | | Transistor bottom leads

Or maybe they just tied lead wires onto them that went off elsewhere? On
this surface this looks like whatever but I am really intrigued by these
vintage components. I see electronic circuits as an art in a way, and it's
kind of a shame you don't see things like this, and hard-wired chassis for
that matter anymore.