Here is a great pic for the panhard thread, you can see their running the bigger shackles to prevent binding
I believe I read somewhere that the Dart actually uses a Mustang style leaf springs, which are only 2" compared to the mopar 2.5" wide version. With the panhard doing location duty, the width of the springs for roll resistance is less important. Current owner has several Mustang racers as well, which may be why he went down that path.
