Just found this on the chevelle forums... remember though that the mounting description refers to chevelles. The Camaro U03 mounting description is in the AIM.
"The optional U03 (low "D") horn is a third horn and mounts on the front, flat area of the inner fender skirt just behind the driver side headlamps. Mounting bracket is "L" shaped unlike the standard horns' brackets that are more "S" shaped. The standard 'low' and 'high' horns mount to the fender lip itself. A relatively rare option with only 1,191 reported ordered."
So maybe the sounds are???
Low note - "F"
High Note - "A"
Tri-Volume (U03) - "D"
That's the same link as before and unfortunately is not specific enough to be 100% re first gen camaros. The chart is for 1978 (plastic horn) chevys. I bet my 68 would have a metal D note horn but i was hoping to find something a bit more definite.
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