After 90 years, I don't think you will be able to definitively answer your question, unless you received some documentation with the set when you bought it. It certainly could be an uncataloged set, as the Chicago era American Flyer company is noted for all sorts of uncataloged sets. Or it could be a set that was put together by a former owner. It's hard to say at this point.
As for the no brass trim, I assume it is nickel trim instead of brass? Nickel trim would indicate earlier production (at least it does in O gauge American Flyer).
