74 Duster- deck between the rear window and back seat

Doesn’t matter if it’s a fold down seat car or a standard rear seat car, the package tray is VERY structural. It ties together the C pillars, the wheel wells, quarter panels, and the bracing from the floor to the package tray, triangulating the whole thing. The fold down seat version just reinforces all the corners, the front edge of the package tray and wheel tubs further to make up for the lack of cross support.

Although it should pretty much go without saying that almost EVERYTHING is structural on a uni-body, at least to some extent.