I recall some of the middle '70s GM cars had THREE copper braided ground straps on them. One on the air cleaner stud to the firewall. One from the rear of each cylinder head to the firewall. Plus possibly one from the negative battery terminal to the body or engine.
If any of them were not there, for some reason, "ground" was found via the console shift cable. Which left things in the particular shift position the car was in when it happened.
I've known of a 3/4 ton Dodge pickup which tried to ground through the rear axle. Or so it was claimed.
Just some thoughts,
CBODY67