There are no differences in how and where the heater box is mounted in a /6 A/C car versus a V8 A/C car. I parted a 74 /6 A/C Dart a few years back and the box was exactly the same and mounted in the same location as the 72 A/C car I have now. The 72 A/C /6 Scamp I had was the same as well.