MARTINSR, thanks for the tips. I have just finished straightening out the rear wall of my cab (51 Chev 1/2 ton). As you mention the supports on the inside of the cab are pushed in about 1/8" - 3/16". I was wonder if I sprayed some sound deadening expanding foam into the gap if that would work in lieu of a piece of tar paper or a piece of 1/8" - 3/16" material. It would fill the gap and adhere the rear wall to the support at the same time. I have removed my gas tank and plan on covering the area with another skin covering the void and filling it with insulation where the tank used to be. Just wondering what your take on the foam would be?
