I don't think it does a lick of good posting these desires here...the McKeen car, the Williams' Midado were cancelled, the three rail market was for a very long time stuck in an endless loop of reproducing the same few prototypes it had once done (!Gracias a Dios!) that we've gotten away from that, if not entirely. Old issues of the hobby magazines are full of all the prototypes, done in HO, kit or brass, that have never appeared in O three rail.
Like auto companies run by professional "managers", with no suspected interest in
cars, just making the most money from toothpaste or whatever "product",(which attitude has not worked for them lately) one wonders if some of the train mfrs. know much about railroad history.
Bobbye Hall (Hallmark) brought in a few side door cabooses in O scale brass. I could
put a long list of combine, side door, and drover's cabooses on here that probably
offered the largest variety and diversity in a train, behind the locomotives. Steam
locomotives offered a tremendous variety, and the Shays, Heislers and Climaxes that
HAVE been made available, as well as K-Line's commuter steamer are a start. Rail
buses and rail cars have been almost entirely ignored in three rail. Of course, maybe
most of the interest is current railroading, and not historical. I don't find current railroads and railroading at all interesting. (don't bother me..I am happily living in the
past)