[DeadheadNM]

OEM rear panels have a cardboard backing that (for lack of a better descriptor) conform to the contour bend of the B pillar and are affixed posterior from the B-pillar by the chrome strips along the top and screwed to the face of the B-pillar, the stands along the quarter panels, and to the rear "post" near the tailgate. This is the best example pic I can post at the moment. There is nothing amiss with your panels. A set of the chrome strips is what you need for best fitment.

It's also worth noting that for single wall tops there are two styles of upper stainless top to bedside trim pieces: one with and one without CST panels.