My horns on my 79 are not working and I was digging thru my spares and came up with a horn with multiple terminals. My knowledge is with 79-86 spiders which only had one tab and one mounting stud on the horn. Both terminals look like they are isolated from ground. The one I found which I was told was from a 74 has the mounting stud and one stub with a tab and one with no tab. #35717 on a couple of spots made by FIAMM. Is it a two tone horn or is one of the connections for different tones/ ground connection?