My oldest piece of still-working gear is a 1923 Stromberg-Carlson Neutrodyne radio, but that is stand-alone, and not part of the main system.
Most of my system dates at least from the 1970s, but I have several TTs and changers that get changed in (pun intended

) sometimes: Thorens TD`124, Collaro 456, and as soon as I get it restored, a Garrard 4HF, all of them from the 1950s.
I'm planning to set up a separate mono system featuring one of these, and as soon as I get a matching stand-alone arm for the Garrard, I'll probably make that a dual-use TT, with one arm for mono 33s and another for 78s.
I think the main system will remain primarily 1970s-onward, as the best-sounding gear I've found dates from that time period. Earlier stuff can sound great, but not QUITE as good as the best of the later stuff. I like using earlier gear for playing earlier recordings sometimes, though, just for the nostalgia of it, plus sometimes contemporaneous gear makes the old recordings sound better (IMO), probably because the stuff was "tuned" using other same-era stuff. Ears haven't changed, even if gear has.