classic auto a/c for a 73 duster will a 72 system fit?
The heater control panel on a 73 is a bit different than a 72. My fan switch is horizontal & a 73 is vertical. Also, your radiator may be a 26" versus a 22" on my 72. I'm not sure where your openings in the radiator support are?
Most of the rest of the kit should fit just fine...
Here's a pic of the heater control panel.