72 vs 73 heater boxes

[swing69]

I've got a 73 Dart Sport, AC car. The harness is chewed up in the engine bay and the under the dash. I also want to get rid of the underdash AC stuff.

I've got a 72 Duster parts car. I'm going to bring over the engine bay and underdash wiring harness. I also want to bring over the 72 heaterbox and dash controls.

Question: anyone have any insight of possible problems? I assume the heater box will bolt up properly....what do you think?

 

[RedFish]

I know there were some changes but I can't say exactly what year. Take a close look at where/how the blower motor is mounted. Mounting holes for the case should be identical. If not a drill will help LOL
You already figured out the controller assemblies are different.

 

[72Swinger360]

If you are converting from A/C to non-A/C the firewalls are different between the 2. The A/C firewall has a large hole for the blower motor and the bolt pattern will be different as well. The non-A/C firewall will have a smaller hole for the blower motor. The simplest way to fix the firewall will be to make a reducer to install the non-A/C heater box. The "correct" way to fix the firewall will be to cut the non-A?C section out of the Duster and weld it into your 73 Dart Sport. The heater controls and bezels are also different from A/C to non-A/C.

Joe