My Shop Manual doesn't include a wiring diagram that exactly matches the 53 (missing horn relay). So I looked around online for one when I found this one for a 1954.

Looks like I'm going to have to extend my horn wire (it's been "shortened" by the PO) so that it can reach the terminal block near the driver side headlight. That would explain the "extra" wire connected to the horn relay that has had me stumped.

I'll fix the wire and give you an update. Then I'll just need to see about that driver side wiper arm.

People keep asking what I want to do when I grow up. I don't understand the question.