Quote
And if he is able to uncover original paint markings that would help to determine if the rear is original how? Answer.....it won’t. Best one can do in this case is to determine period correctness.


Correct, however if all the assembly dates are uncovered and correspond to a narrow time frame around the SPD, then chances are it's the original. Very unlikely that a replacement housing and center section were installed with assembly dates the same as the factory original one.