Question to A/C experts

Some things will work and some won't.
The 73 and newer fire walls and A/C outlets are different than the 72 and older ones.
The 73 condenser is specific for 73 only as the receiver/dryer is attached to the condenser. I don't know about the 74.
/6s have different hose lenghts and brackets.

It is best to stick with the same year.