John,
You might want to post this question in the Paint & Body Shop.
This forum, The DITY Gallery, is not often visited by anyone other than a new member who wants to get pictures and information about his/her truck into the Gallery.
For the most part, the exterior color ends where the exterior sheet metal ends. Follow any area of exterior sheet metal towards the interior. Usually, either the exterior sheet metal overlaps the interior sheet metal (in the door openings, for example), or the exterior sheet metal is "pinched" to the interior sheet metal (as in the windshield area, I think).
