Ok, if you say so Tony. But the word "wood" is not apparent on any of the
drawings. But ONE drawing does have a parts list, and it identifies one of
the parts as
"AAR approved steel running board"
I guess the proof is left to the reader, on the other drawings... :-)
I invite you to inspect the tank car drawings in the back of Kaminski's _AC&F Tank Cars_ book.
Walks are clearly wood, called out as 1-3/4-inch minimum thickness.