Master shut off switch charging problem

Here’s a schematic. The starter relay lug powers the fuel pump, m s d, water pump, starter celinoid. I’m sure a few other things. The wire with the fuseable link used to go to the starter relay. By breaking that connection and the pos. Battery connection the car would shut off.
What is between the alt. And the amp gauge and the amp gauge and fuseable link wire in the factory wiring?