8021 Santa Fe Alco B units.

I have purchased two Alco Sante Fe B units (8021). When I placed the two side by side I noticed that the markings were reversed from one another. I checked the Greenburg guide and is shows the two variations and that the one with the 8021 under the vents as a bit harder to find. The book then asks for reader information on the actual scarceness of this variation.

Given the age of this book and I am not sure it has been updated, does anyone have any information about this unit and how scarce if at all, it really is?

Thanks

Which book are you referring to?