Pickup Box D-Pillar Assembly

A pickup truck box assembly includes a truck bed, an inner side panel, and a D-pillar. The truck bed is secured on a rear edge to a rear cross-member. The inner side panel is mounted to the truck bed. The D-pillar includes an inner part secured to the cross-member and inner side panel, and an outer part secured to the inner part and disposed between an outer side panel and the inner part. The D-pillar inner part includes a U-shaped portion and a first flange extending rearward substantially ninety degrees from the U-shaped portion in a plane substantially parallel to the side panel and a second flange extending from the U-shaped portion outboard of the inner side panel.