Free on-line railroad book.
As I continue to look for information, I am thankful that older Railway Ages and other books are found now on-line.
Here is one, more of a railfans coffee table book, however still good enough with a cuppa coffee to spend some time with and bookmark:
100 hundred years of railroad cars https://babel.hathitrust.org/cgi/pt?id=mdp.39015006059086&view=1up&seq=1
Some of the drawings and cross sections are where this book really shines. James Dick - Roseville, MN