Prototype for the Lionel 6464 boxcar?

[BroadwayPhil]

I am working on "fantasy" paint schemes for a "Lionel Lines" 6464 boxcar in N scale.  As near as I can tell, all actual 6464 boxcars are painted for real railroads except the Timken car (Timken made, and still makes, roller bearings used by railroads) and the 6464-2000 anniversary car, which is lettered for Lionel Corporation, not Lionel Lines.

However, it is the car itself that I am interested in.  As Lionel often copied or modified actual prototypes (the Evans auto-loader, for instance, is modified from a one-off car built by Evans for the New York Central), I was wondering if the 6464 is based on a particular boxcar design.

I have looked at photos but cannot decide if it is based on the Pullman-Standard PS-1 or the AAR 40-ft steel boxcar as built by other manufacturers (e.g. Bethlehem Steel).  Both kinds would have been very common in New Jersey and familiar to Lionel's designers.

Any help would be appreciated.

Phil