Electrical fried for third time

Cudachaser is right. I don't know what year you are working on, but most of these cars came with 35 amp alternators (as I recall). I would go a step farther, though, and rewire the car and improve the charging system, too. Otherwise you'll just drain the battery. Figure out what your load is and work from there. Use the relays if they are necessary for the amp. Some have an internal relay (or more likely a solid state version) so they just need a trigger and heavy power cable.