Thats the circuit breaker for the automatic seat back latches. Your car has the Convience group option (Automatic seat back latches, trunk light, map light, parking brake warning light, headlights on warning buzzer, (think I hit them all)) Early 70's used a circuit breaker there, later cars used a Fusible link. Convertibles also used the same harness and breaker for the power top .... While your under the hood I'd double check the engine to chassis ground (originally incorporated in the neg. battery cable as alot of cars lost that when the cable was replaced). Hope this helps .... John