These are great books with fantastic color pics and technical information about the various locomotive models.
Model Railroading's Guide to Modeling and Detailing Diesels Vol. 1 and 2 by Lee
Union Pacific Locomotives Mechanical Books Vol 1 Vol 2 Kratville Ranks
Lionel Model Train Price & Rarity Guide Vol. 1 + Vol. 2 1900-2003
1999 3 Lionel Legend Trains Catalogs Preview Vol 1 Vol 2 PB Great Illustrations
Morning Sun Books 1762 Reading in the Conrail Era Vol 1 Hardcover Book
DAY OF THE DIESELS Vol. 1 : 1970-1974