This car was built on April 21,1969 and is grabber orange above the firewall pinch weld. Is there a definite date as to when the cowl above the pinch is painted black?
Guess your asking about Dearborn production. Since we don't have real build dates for all examples we have in picture form we have not been able to determine an exact time and shift and as Bob mentioned Ford did not document this change in writing that we know.
For a April 24 69 car - looking at the pictures of cars from that week it appears that it could have been either way since that is about the change over point using the pictures of unrestored cars.
21D built example
29D built example. Car is a Boss so some of the cowl has some black from paint passing through the cowl cover during that process and someone rattle canned the exposed cowl front edge while the cowl cover was on. So that is why that section is black all these years later IMHO., Larger center black below the cowl cover may be the results of the windshield black out
Unfortunately my 24D built car's original paint was long gone when I got it