I used the product shown in the image. I applied to the firewall inside and out , floor , overhead , even the gas tank behind the seat of my ‘54. The noise reduction was dramatic. I have carpet covering the insulation on the cab floor ; after 1 year and 1000 miles the stuff looks like I applied it last week, including the area under my feet.
I hadn’t heard of the brand but I thought it looked promising and potentially cost effective so I initially ordered a small quantity. I liked everything about it so I went all in , no regrets. If I had another project I would look no further. (Amazon)
