@BlueComet400 posted:I don't know if this is always the case, but the "X" often identifies an item that didn't appear in the catalog, such as a department store special / promotional outfit.
Agree......in the John Schmid book there is a list of sets that started with an X......X-500 NA up to X-875.......it seems to be just from 1960 and 61.
I showed these pics in Weekend Photo Fun a week ago......a steam set that was a department store exclusive for Abraham & Straus.....
.......with the uncommon 3386 giraffe car.....
Peter