Those would be 1939 couplers. The earliest, and not all 1938, couplers have smaller vertical sheet metal on their curly pieces. Not sure what you are referring to as solid couplers.
I believe American Flyer used the curly couplers on the smaller cars in 1939 because the link couplers do not appear to handle curves very well on the smaller cars, at least on the ones that I have seen that were converted by others. The link couplers are too long and rigid, so going around a curve requires the end of the frame to be cut completely off in order for the link couplers to have clearance when rounding a curve.
I never said you should not sell it as is, just not to expect a lot for it in its current condition. If it were my set, I would sell it as is.
NWL
