Barracuda carpet help

What is 7 for? I would guess those tangs go forward by looking at the shapes of the driveshaft cutouts. So they are under the front seats...see the front driveshaft shape is larger than the back and the driveshaft tapers from front to back? And it would probably go over the front piece as you woldnt want your rear passenger feet to slide under the overlap... But whatever fits. That 7 piece is a scratcher...? like one side of the trunk?