On my 56 a couple years ago the horn just went off for no reason in the street where the truck was parked. I was trying to get to the battery cable after about 3-4 mins. of constant horn tone and the relay clicked and that was it. Not sure if the relay got stuck or what but it died.
It's been on my to do list to get another relay and go from there. A friend of mine has a 58 and he gave me his since he's not going to be using it.
It has 4 leads. 2 big leads and 2 small. Just curious if anyone knows which is the load and which is the control side of the relay so I can test it out before installing it.