[Martinj]

Do the 5up1 and 5cp1 crts interchange with the 5jp1?

[Bob Andersen]

You should familiarize yourself with this website. It has datasheets for many tubes and CRTs including these
https://frank.pocnet.net/sheets52.html

The 5JP1 is a rare bird with the deflection plate connections coming out of the neck. I doubt there is any sub for it.

[Arran]

The 5JP1 sounds like either like a military tube, or one built for some piece of older industrial equipment.

[Bob Andersen]

https://www.ase-museoedelpro.org/Museo_E...1/5JP1.pdf