1937 & 1940 are outside of my first-hand experience, Joe

There is no mention of two tags in the 1937 Specifications Manual.

Two tags are referred to in the 1940 Specifications Manual. One tag is for Fisher Body information.

Car & truck serial numbers/locations are shown on the same page/drawing in those years.

Were truck bodies made by Fisher Body in 37&40? I do not think that Fisher Body made the 47-55 Advance-Design truck bodies (Fisher Body plants made car bodies in those years, I think).