1968 dart wiring harness help

4spdragtop said
That's starter relay.

Yep and shown is for manual trans. Starter relay for automatic will have another terminal with brown wire going down to neutral safety switch.
Reverse lamp switch for automatic trans moved to neutral safety/dual function switch in mid 1968 model run so we can know for sure where yours is. Inside cabin was low on the steering column or extension harness plugged in there to route to the console mounted shifter.