My W126 had the dual note horns and factgory dash switch for each of these, the town horn which sounded like a loud VW bug horn, and a wimpy country horn, utterly inappropriate for a big Mercedes like yours.

So, I went and bought 2 Cadillac horns from the Cadillac junyard on junkyard row in Rancho Cordova. I am sure you know where it is. Close to you, not far away.

Mounted them just ahead of the wheel wheel on the right side, perfect place for them.

Now I flip the dash horn switch to country, and the 2 Cadillac horns give a train like blast, without the need for airhorns and compressor setup.

It's highly satisfying, very cheap (about $15 A HORN) and a nice upgrade, and you can still keep the VW bug horn note if you want to use that sometimes

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1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...

1995 E 420, 170k "The Red Plum" (sold)

2015 BMW 535i xdrive awd Stage 1 DINAN, 6k, <----364 hp

1967 Mercury Cougar, 49k

2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive (sold)