I have seen a lot of watches where the date of the caseback and the production year of the movement (often out of the official archives) do not fit exactly. E.g. one part is of 1971 and the other part is of 1974. Or a caseback without mentioning the moon is paired with a movement of 1971.

In my eyes it should be OK because the parts were not manufactured just in time. They were produced and used when they were needed.

But what do you think?

 

Casebacks are stamped with the model year, not the manufacture year.
As an example, the -71 Speedmaster where replaced with -74. You won't find any casebooks stamped -72 or -73, but movements from these years, and a bit of -74 as well, is fitted to -71 case back Speedys.

 

Ok, got it. Thank you.

And the model year is beginning somewhere during the year.

So a caseback from 69 can have a movement from beginning of 71.

But a caseback from 74 should not have a earlier movement.