1972 vs 1973 Dash Wiring Harness

I have a '72 Duster that I am going to put a '73 Dart dash and AC system in. I am trying to decide what to buy from a dash wiring point of view. The M&H harnesses from Year One have a '72 A Body and '73 A Body that are over $100 different. I have looked at the schematics for the 2 years and there is very very little difference. Anyone have any thoughts on what the '73 harness would have that would make it $100 higher cost?