Thank you for viewing. This is a set of two books: DD51 type liquid-drive diesel locomotive wiring diagrams and connection diagrams. Book 1: Created March 1966 (Showa 41) Book 2: Created September 1967 (Showa 42) There is some wear and discoloration due to aging. Please check the condition in the photos. These belonged to my father, who was a railway enthusiast, so I cannot answer detailed questions. These have been stored at home for a long time, so please understand and consider purchasing.