This Philco came out about 1940, used loctal type tubes, the Firestone may also been built by Philco ,I've also seen a Slivertone[Sears} like this . I've owned and worked on many of these radios , I think I can come up with a 1940 or 41 ad for this radio, I'm restoring a 920 Philco , I have an original display avertising sign ,witch uses an actual working radio !,It is from 1939, is a mock up of a late 30's auto dash my 920 sold originally for $24.95, I think your 931 sold for $19.95? I'll check on it.
