When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Your best bet for that year truck would be a performance muffler shop.
JCWhitney sells a dual exhaust system. It fits 1965 to 1974 for $125 plus mufflers. I don't know how good it is.