I get that. But if you notice from the pictures, the sliders don't allow the springs to hang down as far as the shackles.......whether that has anything to do with it, I don't know.
I do know this. I KNOW there are LOTS of Mopar cars using the leaf spring rear suspension and running fast. There are also lots of Mopars using Caltracs and running fast........and planting the tires a LOT harder than this car. He's got "something" going on and I don't see a lot of other people coming in here trying to discuss it, so that's what I am doing. Throwing ideas out.