Suddenly no juice

Red I don't understand your logic, here. If you leave your headlights on, and jump your car, that 80A alternator you've installed is going to output 80A back to the battery. And if you've installed a 30A fuse link, I can flat guarantee you that the fuse link is going to blow up.

As I tried to explain to you earlier, most these cars only came with about 45A alternators

(The above are examples, use whatever numbers you want)

Ma knew this wiring was marginal, which is why "she" provided "fleet taxi" wiring for 60-65 A optional alternators, and which is exactly why I preach NOT putting heavier more modern alternators on these cars without changing the wiring.

I can also guarantee you that if you put enough load on the main breaker of your house panel, you'll pop that thing, too!!! You might not even have to do anything remarkable. I might be able to do so by simply turning every darn thing on in the house, pluggin everything in that I can find, then going out and tripping the breaker, and flipping it back on. It will trip from the inrush load!!!!