I infer from this evidence that the underframe with only one stringer
per side was common, if not universal, practice on prewar AAR
standard box cars, and continued to be used on at least some 10'0" IH
cars into the postwar period. Some railroads may have specified only
one stringer per side to reduce weight, others may have specified two
(or even three) per side for stronger floor support. At this point,
which cars had which arrangement is in most cases impossible to
determine, and photographic evidence tells us nothing. Conclusion:
the model underframe with only one stringer per side is certainly not
incorrect, as many prototype cars were built that way, but the two-
stringer design may have been more common on taller Alternate
Standard cars and may have become more common on 10'0" IH cars
through WW II and into the postwar era. In any case, the number of
floor stringers is invisible when a model is on the track, so
personally I don't give a damn. But YMMV.
Richard Hendrickson