Glovebox variances.

Redfish has it right, in 67 the glovebox door was on a spring hinge and didn’t have a lock. Neither did the seat backs of the front seat. In 68, new safety standards were put into place, and in this case the glovebox door was mandated to lock to keep **** from flying out in case of an accident, and the seat backs were made to lock to keep the rear seat passengers from flying forward and crushing the front seat passengers into the dash. Other safety mandates were crumple zones in the top of the dash, hidden under the dash pad, seatbelts became standard items, shoulder belts were an option, headrests became standard, or a high back seat back.