pilot:  ; 203

To get optimum search I put the obvious identical models 203 (75 tube) and X203 together. Now both ways to search will arrive at the model "203 (X203)". And the model with 76 tube is also clearly defined.
To use early and late would not help. A collector looking for info in RM would never find such a hint on his radio. In our case here the tubes are unambiguous means to discriminate.
In addition  "early" and "late" as found in some Sylvania Service notes are in doubt insofar, as both versions are noted for the same year 1936 (Riders vs. Machine Age).

Für diesen Post bedanken, weil hilfreich und/oder fachlich fundiert.