Ben, My database coughs up 639 single-sheathed series, new or renumbered, that are either spot on or an inch or so off from one or more inside dimensions of either ARA 1932, or AAR 1937, or as modified 1941, or AAR 1942 (50 ft car). Some are single door, some are double door, especially the 50 ft 1942 dimensions. I was surprised by the count!