I found a very good site that contains a lot of old advertising information - it has transportation with a subdivision for Railroading. WW II info, and a lot of other useful information including images. Could be used for research, or possibly to print the images and use on a model RR.
This is the main link:
http://scriptorium.lib.duke.edu/adaccess/
This link is for Transportation:
http://scriptorium.lib.duke.edu/dynaweb/adaccess/transportation/@Generic__CollectionView
Enjoy.
Don K