Charger IRS in a 69 Dart!!...
I am thinking out taking the IRS from an 06 gto and using it. It is the same way, a single assembly. I had serveral 04 to 06 gto's (long story), there are a few things about the charger/gto/camaro IRS....wheel hop is a consideration. and even more of a consideration, with the units being a single assembly, the geometry of everything has to be perfect or you are going to have LOTS of tire wear issues and the car wont track straight under heavy load.
You can buy GTO IRS assemblies off ebay for $400 brakes and all