Here is a thread that I saved discussing many different types of sound deadener.
Link inside Look through the thread and you will find links to other threads, articles and test results....
I used Brown bread on the doors of my 77 Cheyenne. Just lining inside the doors and the back of the door panels made a huge difference, It is well worth the money spent. I think they changed the name of Brown Bread, but I'm not sure what it is now.
Great link rauto13...