Factory Primer Color

YY1 said
On my 67 wagon, the original paint is quite thin in several places.

This car is white with a blue interior.

It is apparent that the doors and tailgate have blue paint under the white.

I find this very interesting.

Anyone else see this on their cars?

My 69 has saddle interior and there is tan paint under the bronze exterior colour on the door jambs. It appears that they painted the upper door frames first and then painted the exterior colour. In your case it would be the same for the tailgate.