I have a wreck of a guitar that is usually identified as a Trojan. tpbiii recently started a thread with his thoughts on Trojan specs.
I'm hoping some of the folks here who have researched these 30's guitars can help to define the transition coming from the Jumbo.
Here are a few of my conclusions (guesses is probably more like it):
1. Jumbos all had 3 tone bars, and most Jumbos (but not all) were scallop braced.
2. Trojans and all early J35's had 3 tone bars and none were scallop braced.
3. The first of these guitars (usually identified as Trojans) had the less tapered body of the Jumbo. Do we have any idea of how many really had this feature? Any later outliers?
Mine seems to be an outlier (I think it is 1937) with regards to other Trojan features (no back binding, smaller sound hole, early style french heel), but has the more tapered body as on a standard J35. When I see guitars described as Trojans, this aspect is often not mentioned.
Here's another '37 from the J35 registry that looks to be without back binding, but this one has the round heel. Not sure about the sound hole size. I'm curious what others are known with these sort of features. Can we assume Gibson is just using up parts?