Wiring for starter - help needed

[rechinca]

Fun part about old trucks is figuring out what some chuckle-head did to it before you!

71 C10, originally 350 with a 350 from a 72 Chevelle in its place now. Found a crappy length of wire looped around the ring terminal for the pink wire to the starter. I cut back the PO tape job to find a cut end on a black wire taped into the factory harness along side the pink wire (which is the resistor wire I believe). Front of solenoid has 3 attachment points to it. One is for the lead from the battery, one for the pink, but what is the third for and what do I do with the black wire? Wiring is not my forte, and I want to make sure this is cleaned up properly.