questions about battery disconnect wiring

Here is the problems:

Most of these switches, the second set of contacts are not designed to handle alternator output. Also, dropping the alternator output can cause a voltage spike which can damage/ fail the alternator rectifier diodes. And, a long run of wire can cause voltage drop problems

One way to do this---especially if you have already rounded up enough no 10 wire, is to use the second set of contacts to break the field circuit to the regulator

"Stock 72 duster" This means you have the newer style (70 and later) Mopar regulator some incorrectly called "dual field" and more correctly called "isolated field." Look at the alternator. It should have two small wires connected to "push on" flag terminals. One is blue. This is switched 12V to the field. Break that and wire it to your rear switch, the second set of contacts. You want to use large wire to avoid voltage drop

(A better way is to add a relay but you can do that later)

Here is how this works. If you pull one cable off a battery on a running engine (AND YOU SHOULD NOT DO SO--IT IS HARD ON ELECTRONICS!!!) and if the engine is running fast enough to cause the alternator to charge, the engine will keep on running.

That is why you need the second set of contacts for a disconnect

There is a diagram floating around some place that details a relay/ solenoid............