How Does One Secure the Sail Panel Cardboard Inserts 64-66 Barracuda?

I asked a friend of mine that had a 66 barracuda and he believes that the interior trim sail panel he bought was from year one and it fit 64 - 66 Barracuda's. Now the car is no longer owned by him as he sold a number of years ago so I can't take a look at it. Although the headliner covers it.