IBM vacuum tubes

[Guy N.]

On Mon, 2020-06-15 at 10:24 -0400, William Donzelli wrote:
> > While going through my assortment of old vacuum tubes looking for audio
> > treasures, I found a handful of IBM branded ones.  Mostly 5965, but
> > there's one 5963 mixed in.
> 
> Who made them?

Good question.  They have an IBM logo and "Made in USA", along with the
part number (5965 or 5963) and a bunch of numbers that might give a hint
as to manufacturer.  Any suggestions on how to decode them?

These came to me from my father, who worked in the Vacuum Tubes
department at GE for a while when I was growing up, so there's a good
chance the OEM was GE.