67-72 non ac boxes are interchangeable. 67-72 ac boxes are interchangeable. There are some minor differences in how the controls mount on the dash, but that can be improvised. In 1973 the systems changed a lot. That is when they went to the levers instead of buttons for the ac.
I put 71 dart ac box in my 69 cuda. It was originally a non ac car. It was a lot of work to swap from non ac to ac but worked out fine.
