I do remeber the dummy jack's ,saw a couple once, my father quick the pole climing a few yrs before I was born, work out of a CO then in downtown L.A.
People would not believe the amount of switching equipment a Central Office had in it. I would say the ones in LA were massive. The ones who maintained them were true craftsmen. These guys and women weren't circuit board swappers. They had to find the exact problem even down to a 50 contact relay with one contact sticking. Then they had to replace it one wire at a time all 100 of them IIRC. By the time they retired they were half deaf too LOL.