Iku64, as Don C posted, that is a safety item that by 1972 was on all Ford manufactured passenger cars across the entire product line. The "Steel Guard Rail" was a reinforcement inside the door that was designed to absorb and deflect side impacts in that area and provide greater occupant protection. Since performance was now just becoming a word in the dictionary, safety was one of the new words for the day back then. I had a 72 Gran Torino to take a hit in that area and can tell you they do work!
Since your Mach 1 has the optional Mach 1 Sport interior, the left side instrument cluster clock would be included in that option. The clock was standard only on the Grande. The full length console would have included a clock unless there was a clock already in the instrument cluster. In that case a block off plate with Mustang or Mach 1 would have been placed in the clock location to avoid redundancy. If equipped with the Instrumentation Group, which would place a tachometer in the left cluster, then the clock was automatically included in the console. Appears to be another popular add on to your car.
There is also another column mounted button that is the hazard warning switch. It disengaged the turn signal function and would flash the park/turn signal and tail lights simultaneously.
The original production installed body side protection moulding was held in place with moulding clips and fasteners. Most of the aftermarket and dealer installed were adhesive backed. The labor cost associated with attempting to installed the factory original with all the clips would have been cost prohibitive.
According to the invoice on your vehicle, there are other items on your car that are after the fact but add to a very good looking car!
Steel Guard Rail
Hazard warning Switch
