By comparison the CCKWs are pretty easy.
Look at the is ONE page with TWO pictures... for something as simply as installing/setting the dist. timing:
The draft/road tubes are differnt
One dist has an electrical filter, the other doesn't
One dist has the data plate right next to the cap hold down spring, the other has it centered in the middle of the two springs.
How are you supposed to tell what engine is right for which year??? I know thats a 100% restoration only question... GIs didn't care... but still... they couldn't even use identical motors when showing servicing!
Who has the 'early/late motor' cheat sheet????