Not being sarcastic, just don't like seeing hipshot advice.
This is a unibody that acts as a common ground for the electrical system that is joined together with 40 year old welds with 40 year + old technology, by lazy factory workers,.
Well, ya, you were. Go read what you posted. So once again I'll remind you. If a 40 year old weld is so rusty and weak that it cannot carry electrical current, it is not STRUCTURALLY sound, either. This is not hipshot advice. Back when I had access to stuff like milli-voltmeters I actually did some testing on this issue. You don't seem to want to believe this. So be it. This conversation is over.