I'm helping my buddy Bob restore his dad's '49 Stude pickup and a question came up about insulation between the headliner and the top sheet metal. When I restored my two Chevy pickups in the early 1990's (I restored two cause the first one got stolen 
) Anyway, what I would do is go out to ye olde junkyard and pull some insulation out of the backseat floor area of a couple of Camaro's. That insulation was a grayish felt and about 5/16ths thick, and it pulled up real easily--it was hardly glued down. It didn't cost me more than a couple of bucks. Then I just cut it to shape and glued it to the inside of the top of the cab with 3M spray adhesive. I drove that truck for 9 years as my daily driver and the insulation worked great. We are going to do the same on Bob's Stude, and so I wanted to give my CASO buddies the same tip.
) Anyway, what I would do is go out to ye olde junkyard and pull some insulation out of the backseat floor area of a couple of Camaro's. That insulation was a grayish felt and about 5/16ths thick, and it pulled up real easily--it was hardly glued down. It didn't cost me more than a couple of bucks. Then I just cut it to shape and glued it to the inside of the top of the cab with 3M spray adhesive. I drove that truck for 9 years as my daily driver and the insulation worked great. We are going to do the same on Bob's Stude, and so I wanted to give my CASO buddies the same tip.