[Milsurplus] What is the replacement fr RCA-991?

[john p hutchins]

Group - I need the expert help!

I have seen some specs that indicate that the replacement for a RCA-991 
may be a NE-48/B9A
Yet I received an Email from a supplier that the replacement for an 
RCA-991 is NE-16/7AA

I cannot find and RCA-991 specs online  (:-{  Cannot find specs for 
NE-16 or 7AA
B9A specs sate 80-125V @.002A or 2mA  (no lower than 80V after 100Hrs of 
operation 105V Average)  the B9A seems to have the correct base also.

Thank you
John Hutchins