the squeaky horn ain't worth a hill o beans. What I was wondering is, can the wiring be reached without dismanteling the front end)to disconnect it and install an aftermarket and use the stock wires to power it up.
I added a pair of aftermarket horns on my ‘13 451. The space is very tight! I bought another bolt like the one on the left side and a socket to match. There is already a welded nut on the right side. Pulling back inside fender liner would help too.
I added a set of Wolo aftermarket horns (dual horns) and it sounds like a Chevy only much louder. May add a second stock horn on this car since I have to change the pass side fender right now anyhow. removing the front clip does make wiring and mounting much easier especially if you have large hands...
Mercedes P/N for alternate tone horn is A4515420320.
On my '05 (Grey market) 450 the wiring for the second horn was already in place. It was plug and play. Much better sound with the two horns. Planing to do the same on my '13 451, just have not gotten around to it.