They remind me a set of Tiff's I had years ago. (15+) The glycerin gauges are exactly like them. I tossed the manifold years ago because if you overtightened the valves just a bit you squashed the Teflon seat. Still have the gauges though.
If a nation expects to be ignorant and free, in a state of civilization, it expects what will never be. (Thomas Jefferson 1816)
Those are some of your first "combination" gauge set. The stems on those had rubber seals and always felt loose. The seats were flat, if I remember correctly, and both the seats and the seals would leak after a time. Coating them in refrigeration oil was necessary to keep them from leaking for a while.
"The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
- Alexis de Toqueville, 1835