I have 7 or 8 with quite clear glass envelopes, only slight twinge of yellow
in some.
Have no need, $50 for all 7 or swap something "useful to me".
Are from 'days gone by' used in Motorola / GE low band base stations which
were run at 250w from a pair.
I used a pair some years ago in 2M PA at 600w output SSB-CW output.
al