oldest tube(s) in your system

I used to run RCA mono-plate 2a3s made before 1936.  Those are good sounding tubes.  A friend runs extremely rare and old 252 meshplate anode tubes made in the 1920’s that pre-date the 300A.  He rarely plays the amp because those tubes cost well north of $30,000 a pair.

I have no idea how old are the tubes in my system.  The amp and line stage run Western Electric 348, 349 and 310a, 310b tubes which were around from the 1940's through the early 1960's.  The 348's and 349's are extremely rare.