73 duster ac box into 72 dart

Also, I THINK that 72 was the last year for the fresh air box with the little door that opened.

Negative, my 73 dart sport has the air doors by the feet. It was a non-AC thing, not sure what year was the last for it. I love those doors , they really bring the air in. They suck when you have not opened them in a while and it fills the car with leaves and other crap.
Firewall is different for AC vs non-AC. It also changed in 73. Here is an adapter plate I made to install the classic auto air box in my 73 so it bolts in.

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