[Big Kev-O]

The alternator case is grounded through the bracket that is bolted to the engine block. You can test the connection with a multimeter by measuring the resistance (ohms) between the negative battery terminal and the alt. body. It should read 0.0 ohms or very close. That said you can never have too many or too large of a ground. I have my alternator grounded to the block with 4 gauge wire. My block is grounded to my chassis which is grounded to the battery. It does not have to be braided. It's always a good idea to upgrade/restore the ground wires in these old trucks. At least make sure all you connection points are clean shiny metal. Rust breaks electrical connections.