Thank you kirill_ka and KE5FX.
Looking to get a HP 8563E which is "non-functional".
Current issue is screen does not show up when power switch turned on- may be (hoping) HV power supply (PS).
Saw YouTube video to repair HV PS.
I am hoping I can get the 8563E up and running, but worst case make it a parts bin for 8563A I currently have.
As you said, can't tell until I look inside and compare part numbers.
Thank you for your insight.
As for noise floor and frequency resolution, luckily that is not critical for me right now.
John N6VEG