Hi, Bob.
The Williams F3 is very similar to Lionel's postwar version which means it's a "hodgepodge" of a bunch of details and not correct for any particular phase. Given that the Williams model also duplicates the dimensional innaccuracies of Lionel's unit, the use of the term "scale" is misleading as the former Williams management had a somewhat loose interpretation of "scale."
I hope this helps.
Bob