[Arran]

Buzz;
  I think that someone replaced the speaker in your 430-H, the original one would have had a rectangular rear bracket holding the pole piece, field coil, and hum bucking coil, yours has one with a round bracket kind of like a Rolla or Lansing, and looks like it's painted gold so it may have come out of a Zenith or something else. The reason I think so is that the speaker cable looks like it was cut, spliced, and wrapped with friction tape. A guy on You Tube called farmall1938 has a restoration series for a 420-H which is a similar but cheaper model then your 430-H but more importantly his still has the plastic dial escutcheon that is missing from yours and the original Stromberg made speaker.
Regards
Arran

yes. its a replacement. we will look at it in part 2

Buzz;
  If that did come out of a Zenith you could very likely find someone willing to trade you not only a correct Stromberg Carlson speaker but maybe a 1939 Stromberg parts set for it. But at the very least it looks close enough electrically that it should work in the meantime.
Regards
Arran