Magic eye tube rebuilding

[AlekZ]

Thank you . Here I talk a little about my magic eye tubes. Since this is in Polish and you may not want to listen, scroll to the next link.

https://www.youtube.com/watch?v=7epxTy-p32k&t=1065s

Maybe this three-color lamp will be a bit crazier

https://www.youtube.com/watch?v=7epxTy-p32k&t=1243s

[Videotechie]

This whole thread is very interesting.
If someone has a direct substitute of any kind for a 6u5 tube would be great.
Any info on this in an English web site link or video would be helpful.