J31 is the option code for dual horns so, yes they were an option. Seems most cars got dual horns but not all. I've had several base line cars with one horn.
Dual horns were also included with other option packages.


72 Satellite Sebring Plus 440, 72 Dart 5.9 4-spd, 68 Valiant, 73 W200, 78 D100 sb, 78 D200, 98 DAKOTA, .
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