In this case the tubes would in fact be interchage. You could easily use one for other. Here is very important part; tube manufacture are different from chassis manufacture. That tube maybe used in tv set, maybe used in arcade, maybe elsewhere. But tube itself will not change if EXACT model number (sticker direct on tube). keep in mind that tube model will have different model within it as you see here. Not sure what each model within is exactly but all will be electrically function the same as all will follow same kneck pin. In this case CR-23. So pin 9-10 heater, pin 8 red cathode, pin 11 blue cathode, pin 6 green cathode, pin 7 G2, Pin 1 focus, pin 5 G1.
A68KJU96X (4F) - Astro City (MS8 chassis, so not fully compatible...)
A68KJU96X (6B) - New Astro City (MS9 chassis)
A68KJU96X (6C) - Egret 2 (MS9 chassis)
A68KJU96X (6E) - Egret 2 (MS9 chassis)
A68KJU96X (7C) - Windy (PB6643-1 chassis)
A68KJU96X (7D) - Windy (chassis tbc...)
A68KJU96X (7F) - Egret 2 (MS9 chassis)
A68KJU96X (7I) - unknown (MS9 connections)
This expand on that idea now. Here is also very important part; yoke and chassis are pair together from other random company...not necesarily tube and chassis paired. example nanao get bare tube from hitachi and have to create chassis and yoke that match. That is how you get many compatible tube with one set chassis and yoke (assuming correct size, correct heater voltage, correct g1 voltage, and correct neck connnector). In massive number of arcade mon tubes you will be either CR-23 or CR-31 neck connector. very standard. grab 100 arcade tubes and you will get almost all of them that. They will follow pinout throughout other same series say CR-23 tubes. It very very common to see 6.3v heater, 50v, cr-23 to use a tube. You have to know these number when connect tube test machine check emmision. So you get screen same size aka "a63" 25inch, "a68" 27inch, (Axx = cm view area first numbers of tube) and you will be able to use chassis at least from electrical point view. When you run into flat screen crt, weird curve, viewable line, etc you will have convergence geometry issue as well... not chassis problem as far as it know. You can easily pull yoke off tube (while still hoooked to chassis) and chassis still run exact same it see no difference. in fact you can pull yoke off while running and see yourself. Tube still does it's thing. Still electron gun firing, still heater etc because it follow standard pinout and kneckboard still provide those values, only deflection will be crazy off. Don't do that though because you will burn phosphur at tube face since you have no deflection. It'll just fire straight dot and light one small very center area that will burn. Some of that make sense?
Here is CR-23 diagram that all CR-23 tube need to follow (or else they wouldn't be CR-23)
Here is real world example with written on kneckboard location each (this from WG D9200)
Hopefully that's all correct for you, maybe little mistakes in there but gist is there.