C3 Trunk Back Wall Piece

[charlesorosz]

Hey guys, here’s a problem I need help with:

So I picked up a new project, a 1975 C3. The carpeting and everything was taken out, but included in the purchase. It came without an antenna, so I bought a new one and the cable to run to the radio. My problem is this:
Now that it’s time to start laying down carpeting, I’m wondering if this grey fibreglass piece (in picture below) is necessary for the back wall of the trunk?

Keep in mind, the taillights’ and other wires are running from the back of the car to the battery and fuse box right now. It has some sort of white box (in picture below) attached to its wires, and have no idea what it is. I assume I just need to carpet over that, as well as the antenna cable, right?
I’m confused as to how I’m supposed to install this fibreglass piece. What material should I use to make sure it doesn’t fall over?

Also, as you can see in the pictures, I have wires going from the back of the car into the battery compartment. But, once I put the carpeting in, as well as the drawers for the 3 compartments, I’m sure these wires will get pinched so there’s no way that’s how they came wired from the factory.

Can anyone with experience carpeting these cars give me some advice on what I should do here? This is my first DIY project, so I’m learning as I go. Any tips and pointers are greatly appreciated

Thanks!

 

[teamo]

I believe that the white box is the seat belt interlock module. This was part of the seat belt interlock that was federally mandated in 1974 and was discontinued in late 1975. If you look on the firewall on the right side there was also an orange colored relay that was part of the interlock system. I also have a 1975 and these parts were missing when I got the car. Someone jury rigged a bypass for the interlock to make the car start without it. As far as the back panel I'll have to take a look at how mine is fastened. It is probably riveted in as a lot of the parts of these cars are. I would put it back because it will probably give the car some structural rigidity.