[Arran]

Kirk;
  In terms of the power output stages the 38-3 would be inferior to the 38-1, since the 38-3 employs that goofy screen grid inversion setup Philco liked to use, I other then the "magnetic tuning" (or AFC) feature of the 38-1 I don't think that there would be much difference in the front end. Since the 38-1 was a more expensive set then a 38-3 that may explain why they at some point ended up with left over 38-1 cabinets, or ran short of 38-3 cabinets one day back in 1938.
Regards
Arran