I am often wrong, but I have before me one of three "Pocket Spotter Guides."
First, it clearly spells Gray with an A.
Copyright 1973 by Frank Diedrich, Waukegan, Ill. Model Graphics Publications
There were three - Two locomotives and one freight car. I believe you can still get them for a very reasonable price from Bill Davis, of American Scale Models. Do so - they will answer all of your questions.