Thanx for the "digging" , and nice result.
Unfortunately it seems like those fans won't cut it as a replacement for the original Pabst 612 - in an Agilent 6632B
The Pabst 612 (6..12v operated) is noisy like h.... but delivers 40m3/h or 24CF/min
The ones you point to only delivers max 29m3/h
I would have loved to get a more silent fan for the 6632B's , but these aren't the ones.
I have found a replacement , the pABST 632 NU (33dB) , it has same specs as
the old 612 (40dB)
But i can't find anywhere to buy it in single q's EU :-(
Maybe it's to new.
/Bingo