I had a funky switch on one of my overheads, and had a replacement on hand, but hadn't gotten around to installing it....'till reading this thread. I decided to move it to the top of my list this weekend.
while I was out there, I snapped a couple of pics of the fixtures, for those that are not familiar with these 70's gems. the "3-way" switch gives you the option of turning on 2, 4, or all 6 bulbs. behind that screen is the crank-up roof vent. in the first pic, you can see the hole remaining from my old skyliner antenna, as well as the new position for the winegard. (mentioned before).
note Andy's reproduction covers in action.