Realized today that we've have posted in threads pictures of unrestored cars and the paint transition "lines" from body color to interior color for San Jose and Metuchen but not for Dearborn. In an effort to address that I offer the following.
As a reminder the interior color/paint was applied before the exterior color (dash, a pillars and door inner surfaces) and masks of some form were used to protect the painted surfaces that wanted to remain. Over the years painters found it was just easier and likely neater to locate this change over with the weather strip so we have seen decades of this practice
Shadows/irregular edges may have been produced by applying masking tape in some areas holding down the long run between the bottom corners from blowing up and out as the spray gun passed over at angles
On some of the examples where the interior and exterior colors are very close to one another I posted another picture with the exterior color surface highlighted
5F07F1279xx
Mid January 65
5F07C6787xx
5F09A6893xx
Mid June 65
Only upper rear edge paint detail I found a picture of so far in my collection from 6F08C2482xx
If you compare these and the examples from the other two plants you can see similarities and differences due to the different workers and what worked for them but there are patterns and habits that always seem to develop over time on an assembly line
Hope these help others in their restoration efforts
