If you can,t find one just for the D318 then a D6 8U & 9U or a 977 20A are the same engine so are pretty much all the same except a couple small items.
The manual you are looking for is Form FE30238-4 and is called
"Servicemen's Reference Book"
(4 1/2" Bore 6 cylinder)
D318 Industrial
D318 Electric Set
D318 Marine
N0. 12 Motor Grader
etc
etc.
D2-5J's, D6-9U's, D318 and D333 power units, 12E-99E grader, 922B & 944A wheel loaders, D330C generator set, DW20 water tanker and a bunch of Jersey cows to take care of in my spare time😄
The manual you are looking for is Form FE30238-4 and is called
"Servicemen's Reference Book"
(4 1/2" Bore 6 cylinder)
D318 Industrial
D318 Electric Set
D318 Marine
N0. 12 Motor Grader
etc
etc.
I have 1 spear servicemen's reference book form 30238-2