Yes! I know exactly what those are!! I have a 1969 Mercury Monterey. I recently cleaned out my trunk which is bone stock and original. Those are cardboard like but thicker material and they go on either side of the trunk under the vinyl trunk liner. They sit on what I would call "hips" on either side on the raised up portions that arise from the bottom of the trunk. They are meant to provide support for the flimsy vinyl liner as it extend outwards towards each inner fender panel. Since there is a 3 or 4 inch gap beside the fenders, these support panels, which will lay in a flat orientation, will be under the vinyl liner. Make sense?
Answers
Those are cardboard like but thicker material and they go on either side of the trunk under the vinyl trunk liner. They sit on what I would call "hips" on either side on the raised up portions that arise from the bottom of the trunk.
They are meant to provide support for the flimsy vinyl liner as it extend outwards towards each inner fender panel.
Since there is a 3 or 4 inch gap beside the fenders, these support panels, which will lay in a flat orientation, will be under the vinyl liner.
Make sense?