301A and 201A are the same tubes. CX301A will be marked Cunningham, UX201A will be RCA. Most likely the missing tube will also be an 01A. In some cases a 171A was used as an output tube. Both tubes have the same basing but 171A requires a higher "C" voltage.
A lot of radios built in the 1920's are not in Rider. Most were similar. Click on resources, above and go to Stewart Warner model 300. You will find a page with several schematics which should be similar to your radio.
Norm
:I bought an old silvertone neutrodyne from about 1927 and cannot find a schematic or tube layout for it. This is a six tube battery operated console, and one tube was missing. The tubes in it were (4) 201As and (1) 301A, although the 301A may not have been in the proper socket. There is no model # but the ser.# is A4979. Any info. or help would be appreciated
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: thanks Ron