73-87 chevy to cummins wiring
You dont state if its gas or deisel harness.
I wish i would have had a gas harness for the most part
but any how your distributor power wire goes to your pump 12 v hot supply to
kill the engine then the rest of the wires goes to the starter and so on
on the grid heater get a ford type real starter switch or a 6. 2 one
and a push button switch for a fair amount of amps hook both wires to the grid heater terminals , one one to the switch , and to the switch to the realy to make a hot connection when the button is held on , hold for 30 seconds to pre heat and fire engine .
the alternator depends upon your alternator etc