The inner trim bar is a fairly thin sheet metal piece and is, like Mark said, separate. It has the sides bent over in a "u" shape towards the windshield, and is secured by oval head phillips machine screws that engage the threads on the external stainless trim piece.
Apparently the later trucks just use the flat tabs that are secured under the inner trim piece as that was all that were on my truck. There was no evidence of a screw hole like fonz8261's photos show in the center of those "unidentified" pieces.
