Not sure what plates you are referring to. As far as I know the headliner is just glued to the inside edge of the roof line and wrapped into the window channel. The there is a rubber trim "U" channel that is pressed on over that to hold it in place. Same at the rear window.
The brackets that (Firebob) are referring to are the pieces that the head liner wrap up into on the front and back of the car. They have those small little sharp metal tabs that help hold the headliner in place.
