All right, I think I am figuring out the pieces to this puzzle thanks to the subtle push from Dan P. Let's go back to the WM21H9A311602 car with the "B" marking I posted above. The dealer invoice indicates a "Special Package" which I think we can safely assume is the "Scat Pak" package, see below. The tag for this car does not indicate a vinyl roof, so we deduce an A40 code exists on the build sheet.

One of the tire options available is the "F70 x 14 Belted BSW with Raised White Lettering (T87)". It sure smells like F70 B belongs to the T87 code. I am off to the broadcast sheet library to search out the T87 code....

D

EDIT: The tag for this car also has the V21 code which was only available with the A39/A40 package. Scat Pak package confirmed....