The GTO suppliers like Ames or Perfromance Years have it but I would like to talk you out of it. It is too heavy and you really need to bake it in to get it to fit. There is much superior and lighter stuff to use now. http://www.amesperf.com/
Check your local lumber yard or home center for what I'll call ice shield, used under roofing shingles. It comes in a 3' roll, about 1/8" thick, and quite sticky. I used it, it formed quite easily with the use of a heat gun, or wait and do it in the summer heat.
DynaMat is the only stuff to use: forms to the floors, and kills sound and heat. This is one of the best things I have done to my car.
The original stuff is like rolled lead sheets --relly stiff. Brad told me they baked the factory cars to ever get the stuff to lay out. It is really rigid when you get it in a roll. The last I put in was cut just like the original pieces which but was a modern sound barrier. It installed without a lot of issues . It was made by a company in Ormond Beach Florida and was cut just for A bodies. I need to try to locate the name. I think I posted the name here once.
This looks like what I used last time. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=180025279493 I might add that if you look at the shape of the cut this company from Ormod Beach uses in the Ebay ad and compare it to the old factory tar paper stuff the shapes of the pieces are the same but it is so much lighter and easier to install.
