Help needed engine harness

73 Dart 318. I just received a engine electrical harness. This picture is of driver side fender. I can see that the red and yellow wires pictured need to attach to starter relay on side of fender. There is a black wire with an unrecognizable L shape boot connector that runs beyond the red and yellow wire on the new harness ? Where in the heck does this wire go ? And I can’t see to eliminate the old harness because it’s intertwined to the headlight harness here. What do I need to do here ? 2nd picture is same location. Aim holding old harness that has that red/yellow wire and I can’t see how to eliminate it when the horn wire and headlight wires are intertwined ?

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