oldest tube(s) in your system

Cunningham 71A tube, in Tektron preamp (Italian company), this tube in production  from 1927 to early 40's, don't know exact date of mine. Also have any number of various 50's era tubes running in a number of  components.

 1950s RCA,and 1958 Amperex  all are Black plates D getters.

@audioman58 what kind of tubes are the RCA and Amperex and what are they in?

Other oldies in our system are: 2 x 1952 Sylvania T-plate 6BL7 GTA and 2 x 1958 Western Electric D-getter JW 2C51.

I have a set of Wurlitzer amps that were modified to run a pair of 45s. The ones I've been using are pre-war but I don't know how old. They run fine. Those amps are no longer in my system, having been replaced by a single amp of similar power that is much more compact. It uses EL95s from the 1960s.

Yea, I figure 45 or 2A3 or similar would be about the oldest tube type still heating listening spaces.  Funny that as those are power tubes; would've thought signal tubes would be more likely to be oldest still in use.  All of our power tubes are new production babies.  And all of our signal tubes are older than me!