[Arran]

I'm just a fellow that likes making adapters so that the set can easily be switched back to original at a later date, I've done this with substitutes for magic eye tubes, when there is room. Basically you take the base off the dead tube, clean out the pins, take the socket you need to use for a substitute tube, and solder some stiff leads onto the terminals of the tube socket, longer then what you need, insert the leads into the appropriate pins of the old tube base, use an ohmmeter to confirm that you have the right lead in the right pin on the old base, and that nothing is shorting together. Then you mix up some epoxy, or use windshield adhesive, and glue the tube socket into the top of the old tube base, solder the leads into the pins, cut off the excess, now you just made an adapter. You can make a shorter adapter by cutting down the olde tube base, but you usually only gain about 1/4'' by doing so.
The same technique allows one to use more modern, cheaper tubes, for testing in 1920s battery radios, people have been doing this for years as a sub for WD-11s, and 199 tubes.
Pdietin;
I was wondering why they had bothered putting a shield can over top of the rectifier tube, in some radios where they used a mercury vapor rectifier like an #83 they did this to cut down on electrical interference, but with a 5Z3 it was hardly necessary. In Canada they tended to skip certain model chassis, like if the chassis was used in a U.S model that had a magic eye, and another that did not, they produced the version with the magic eye but skipped the one that did not.
Also RCA in Montreal and C.G.E in Toronto had their own production lines making the same sets, by the late 1930s they made sets that were not produced in the U.S, though the AC/DC models were. We also had Canadian Philco models that more unique, sometimes including an RCA jack. The common thing was that Canadian models seemed to have more shortwave bands, even after the war.
Regards
Arran