Most delta guns are electrically the same. The only thing
that differs as a rule is the HV. Over the years it went form apx
< 25 KK to a little over 30KV The other major change was to black
matrix Zenith "Chromacolor"' "Super Chromacolor" and " Chromacolor 2".
Any from the 25AP & XP on can be used as a test jig for any D gun
set as long as you keep the HV in mind.
Zenith built CC tube replacements for the AP & XP but I dont remember the numbers. I even put on in my parents Y line Zenith. Z line was the
year things started changes fast. Transistors were taking over.
73 Zeno
LFOD !