OK thats what i thought,so witch side of batrery, the (-) side? and or witch terminal on the relay??
The battery connection on mine runs to the right side of my starter relay, which is the side connected to the battery negative lead, not the starter cable side. Mine is 6 volt positive ground, but that makes no difference for the way the horn relay is wired. B goes to Battery, or power, whether it's 6 or 12 volt, positive or negative ground. B does not go to ground, it goes to battery voltage. It's how the horn relay provides power to the horn(s). The horn button (Switch) provides the ground to complete the relay circuit.
Some others can weigh in on this but do you really need a horn relay with a single horn? Your vehicle never had one. Of course it was 6V but still . . . it isn't like you are using your horn a lot. Or do you? A relay normally is there to provide a low amperage circuit that will reduce arcing. I'm not sure that a single horn needs it even at 12v. I subscribe to the KISS principle if at all possible. Lets see what everyone else thinks.
Attached are some wiring diagrams. Note that a wire supplies battery voltage from the circuit breaker on the back of IP to the horn. Then the wire from the horn button runs down the center of the steering column, through the firewall and out to the other horn terminal. I'm not sure if the terminals on your horn are marked but I'm not sure that it makes a big difference which wire goes to which horn terminal.