In 1973 GM/Pontiac was one of the first manufacturers to use RTV as a gasket replacement. That application was for the Pontiac valley cover gasket.
I always bought GM gaskets from the local Pontiac dealer as it was usually cheaper, and you didn't end up with a bunch of unused gaskets that you threw in a drawer. or set on a shelf. In 1973 I went in and asked for valve cover gaskets, and a valley cover gasket to repair a 69 GTO I had recently purchased. The parts man handed me 2 valve cover gaskets, and a tube of black RTV with a GM part number on it. I of course inquired where my valley cover gasket was, the parts man explained that GM had superseded the RTV for valley cover gaskets.
Long story short, I used the RTV. and haven't used a valley cover gasket since. It's kind of like the chevy guys never use end rubber seals for their intake gaskets anymore. The RTV is superior to the gaskets IMO, so I'll keep using it.
