Not sure about the direct answer to your question - but I have an early 1940"s AC Dealer Master Parts List that covers ALL models. Its broken down into sections like Front End and then subsections for each Major Model - though there are some tables that show B, C, IB, etc which share some common parts. It has had updates added as late as 1946 but other page dates go back to 1942.
As to the D-26 Parts Book for B, IB, C, B125, & 60H, I have Feb 1950, Apr 1954, and June 1964 versions. Earliest of other Individual model books I have is D3 for WC, WF, W201 dated July 1947.
I also have TPL-28E for B Tractor dated Dec 1939 which was a combination Operator Instruction with Parts List.
So it would seem that early tractors (pre-1940s) included a Parts List with Operators Manual and later tractors (after mid 1940"s) had a separate Parts Book. You may have one of the earliest of these.