Today I ran 2 new grounds, I ran one from the firewall to the negative battery terminal, and a ground wire to the firewall to the starter that was missing.
The negative battery post is grounded to the body
https://www.trifive.com/garage/56%20...nual/12-12.gif , The body is grounded to the engine at the lower starter bolt
https://www.trifive.com/garage/56 Chevy Assembly Manual/12-15.gif The frame is not grounded.....However, if you have a strap, you can ground it to either the body or engine.
I noticed when I ran the new ground wire my turn signal worked on both sides of the instrumental cluster panel whereas it never did before.
https://youtu.be/gkhXA00Ae8I