This is a fun read. Copy right is 1955. It’s by General Motors Corporation so as far as the diesel part goes it focuses more on Detroit’s.
I got this copy from a friend and it’s missing the cover. I think the original cover is red. It’s only 100 pages.
As I remember, zip codes replaced zones in 1959. At the time that manual was published, Detroits were by far the most common marine diesel in boats. Even Russia, who received some in Lend-Lease tanks and ships, was making a copy of the 671.