[Kube]

This thread seems to have turned in to a discussion of gauge steel.
I have to wonder, with Ford owning his own steel mills, perhaps he did not "order" the steel by gauge but rather a tighter tolerance than "gauge" acquisition would otherwise allow.
While employed as a tool maker, I knew that much of the work we did was for the military and as such, "gauge" was not good enough and steel was ordered and subsequently supplied to a much tighter tolerance. The cost of course increased dramatically "up front" but paid off in later processes.

By the way, as I recall, the 1939 & 1940 open car frame rails were a nominal .110" thick while the closed car frames were a nominal .100".

Perhaps DavidG can weigh in here in regard to what Ford may have demanded of their own mills.