I don't. The one I have is for relay equipped trucks. I figured that out after the fact. I have the correct one on order. I'll be adding the relay back eventually, I'm just satisfying my curiosity on the original setup first. The old sparton horn worked off a relay with the original (non-relay) horn switch in the wheel.

Seems I did read somewhere that the relay type switch can burn up when connected without a relay? Dunno.

Checked voltage today on horn feed, 6.4 volts, same as battery. Horn works when hooked direct to battery so I've kinda isolated it to my button setup and or a ground.

1951 Chevrolet 1/2 Ton
http://s2.photobucket.com/albums/y7/pikappa167/1951%20Chevy/