that's not the part number its the reference in the parts book to the section in the parts list that will have the part numbers for the various cars. for instance... the same 23-64-40 will have part numbers for Imperial and Plymouth and dodge lines. some of the part numbers will be the same some will be different.
23 is body
64 is Window and Vent Wing
40 is the rod and nut
44 is the retainer
this is from 67 parts book page 23-106 (page 1029 of the pdf)
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