I was surfing the web and came across this company AcoustiShield based in Stockton, California and they make and sell ready to install pre cut insulation kits for 1964-1970 Chevy/GMC vans. I called to make sure they were still making them and they are available for all years. Yeah its a little pricy but I thought I'd put it out there anyway.
Their website is: www.quietride.com
here is one page of the 7 page PDF I was able to download from the website.
Their website is: www.quietride.com
here is one page of the 7 page PDF I was able to download from the website.