THat was something that I wondered about before. The way they altered the wheelbase.
Do the 66-70 B body cars all share the same dimensions? I mean center to center of the K member mounts to the torsion bar crossmember, to the rear frame rails, the front mounts of the leaf springs, etc.
For years I ran Super Stock spring hangers in my '70 Charger. I drilled a hole up high on the bracket to effectively lower the car. I later decided to raise the car and needed brackets. I had parted out a '68 Satellite Station Wagon and used those. The tire was really close to the leading edge of the wheel opening. I had to rummage around and was able to find another pair of brackets that had the spring eye mounting hole further back. I never knew exactly why there were different sizes. I've parted out A-Body cars and thought the hangers were from some Duster or Dart. Now I wonder if they were the original ones from my car!