No problem,,,,,,a lot of things happen to the vans in 50 years,,,,,,,you need to find out what you now got,,,,the system is that 12 volts leaves through the small wire on the positive battery cable, it goes to a screw on the horn relay,,,,,those screws are a junction block,,,,the horn relay gets it power there for the horn,,,,the voltage regulator gets its signal there and the alternator output goes there,,,,AND the feed wire that runs forward that feeds the ignition and headlight switch as well as the fuse box also goes there,,,,the horn relay is in charge of the whole electrical system,,,,,,BUT that 7 wire connector by the carburetor usually is a problem,,,,,,the ignition switch sends 12 volts back to the coil through a pink wire,,,,,HOWEVER,,,,the coil only needs 6 volts, so there is a special Orange/white/purple cloth covered wire connected to that connector that cuts down the voltage before it gets to the coil,,,,,so see what you got,,,,,we can fix anything here,,,,,one step at a time,,,,,once we dial in what the problem is,,,,,