ISTR that the FAA in Los Angeles still had some Bendix digital stuff
from the late 50s/early 60s in daily use - part of the
LA radar complex.
There were a couple of articles in the Times about how the techs
who knew
how to keep the old stuff going were ready to retire - and the difficutly
of finding some of the tubes.
I don't know if that system has been upgraded by niw - this was ten or
so years ago I think I read that.
It would certainly qualify...
Cheers
John