Wrong heat control

You definately have a mismatch there.....the face plate is correct for a '73 but the control is an earlier one. The '73 control should be a lever type with a verticle fan control in a plastic housing. The one you have is a slide control with a metal housing. It looks like they trimmed an earlier face plate to be used with the early control and then trimmed the later face plate to get it to kinda-sorta fit together. To get it correct for '73, you would need a face plate and control assy. at a minimum and maybe more if you want to get the heater working. The A/C controls used vacuum to operate the flaps but the non-A/C cars used cables so they may not work with your heater suitcase.