Noticed that my horn sounded different as I honked for some deer, went to check, and look like one of the bolts may have rattled loose and the second horn fell out, leaving me with only the very high pitched one.

Does anyone have the pitch of the two horns for replacement purposes?

 

My '90 GXL came from factory with only one horn.

 

I'm not sure what exact note pitches the specific horns are, however I can say that all S4 GXL's had 3 horns from the factory (the FSM also reflects this.)

Two of them are for the regular horn (high and medium tone) activated with the horn button on the steering wheel. There is a third low tone horn that only sounds in addition to the regular two if the factory alarm sounds.