Hy 57 Apache Stock, I have a very limited supply of true American parts books, and I would never argue with Mike B, but here is some information I found in an American Chevrolet parts book which covers 1955 (second series) to 1960 2 & 2 1/2 ton trucks. "*Note: Numbered in sequence commencing with 1001. Engines are now stamped with a source, production date and type on serial number pad."
Example:F104 (F) (1) (04) (N)
Plant Month Day Standard 8 cyl."283"
Flint January Fourth Series 5000
I have no idea if the code letter "N" is the same for a 1957 3100 V8 or not. Just as a side note 1957 Canadian Chevrolet half tons (1300) did have 283 engines in them. Hope that helps some.
