I got my insulation off the inernet. There seem to be three major kinds. One was way to pricey. I bought some in the middle range for about $100 as I recall. I think it was called something like"Be-Quite". It is about 1/8 in thick, very sticky black with aluminum backing. It came in a 12" role and very heavy. It's almost impossible to take off after you sick it down- like contact cement. And very messy. I learned the hard way not to let the black touch anything. But I think it will really do the job when I get my truck on the road and it's not going to fall down for sure. I did the whole inside of the cab, including inside the doors.I glued on a second type of insultation (for heat) under the headliner. It was hardward store stuff but with carpet pad looking material 3/8" attached to the aluminum.