notchback question

There should be a layer of sound-deadening material between the back of the seat, and the cross bracing. The top of the material attaches to the top cross brace, hangs down, and runs under the seat bottom. There were slots cut in it for the hooks on the top of the seat back to go through.

The original material is sandwiched between two layers of thin, black plastic sheeting (similar to a thin plastic trash bag). It's also used behind many of the interior panels. I replaced mine with this "Super Insulator Mat" from Summit Racing. It has better insulating qualities than the OEM stuff.