A little more info - if the ends are what I think they are, the top corrugation was usually (always?) flat along the bottom.
The B&O and some of the SP cars had poling pockets. I couldn’t verify the others with the photos handy, although I think many of them did not. Most of them appear to have a more triangular shaped “tab” at the bottom corners, rather than the square appearance there.
Modeling the New Haven Railroad 1946-1954