Here are some more on numbering systems. The first two pages are from a T-28 Parts Catalog, but should apply to any NAA aircraft.
This is from a Stearman Parts Catalog. IIRC you had some duster parts, so it wouldn’t be unreasonable to assume that you may have some Stearman stuff. Look for part numbers that start with 75. If you have any aluminum castings that have 75-1100 series numbers or 75-1200 series, those are particularly valuable!
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