i belive on that BLOWN 502 MONTE there should be a fuseable link wire coming off of the bat. that goes to your alt. and horn relay, then it leaves the horn relay and go to the fuse box as the main hot wire. get the horn relay hot first and hoprfully the rest will fall in place. ive got a 70 chev. wiring diagram that im try to down load and if i can ill get it to you.