I bought the horns that are the nice 'correct' ones to complete the repair of that system in the 65. I added a relay and used the regular wire to the horns to activate the relay. The relay part worked great. What didn't was the HI horn. After a short troubleshoot, the horn has ~3.9 Ohms from the lead to the giant rivet that holds on the bracket, and OL (infinite) between the rivet and the bracket which is the ground connection. I know what happened here. It is definitely a manufacturing issue. The paint appears to be a powder coat because of how much it fought back trying to clear off the back of the bracket for good electrical contact with the chassis. The bracket must have been coated in a way that prevented the rivet from making electrical contact. Usually in this type of construction a piece of tape or a sticker is used to prevent paint from getting on the part that needs electrical connectivity. Guess they ran out. The bracket being fully painted should also have been a clue. Maybe I was just lucky with the LO horn having bit into the paint when built or something. Time to go through the receipts and see what comes of it.