It would appear the Cadillac Hood Crest/Ornament has been Photoshopped out of every single image in the book. I wonder if it has to do with copyright infringement.
If it was a matter of copyright, I'm not sure the book would've been published at all if they hadn't gotten permission from General Motors (the current owners of the Cadillac brand) to reproduce the look of the car. It's an odd development, certainly.
It's just has to be a legal issue. Keep in mind that when originally issued a title, they were no longer considered Cadillacs by the government. They would've been considered a Miller-Meteor, Superior, Eureka, S&S, etc depending on the respective Coachbuilder, and Cadillac lost their rights to the car, in theory.