That 60-something year old braided ground cable looks good, but I'm beginning to think it might have been part of the problem. Leave it there for eye candy, but add a heavy engine-to-frame ground somewhere else (maybe on the driver's side) just for good measure! That will also help with providing a good return path for current from the lights, instruments, and other low-current devices. A few 10 gauge wires from the frame to the bed, cab, and front end sheet metal will assure that the electrical path back to the battery doesn't get compromised.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!