Even within the same plant in the same month there are differences.
Lots of different employees, different shifts, temperature & humidity when the car was dipped, sprayed, etc., etc.
So........
Your car was there when it was built, so it is the best evidence you can find, explore & discover all you can.
Record the details with a camera & start a file.
Document what you find on your own car & then put it back to the same way, anything less (or more) is not a true restoration.