Flattened a leaf.

I'm not trying to add to trouble shooting the spring problem, but I have a (educate me) question. I've never seen this type of leaf spring application. (old school here) What is advantage to having the leaf springs on a sliding shackle?
Norm

Leaf spring sliders are as old school as you can get. They allow the leaf springs arch without binding and make the rear of the car lift on launch planting the tires. Kinda like the whole Mopar rear suspension as designed........without the sliders. I never saw a use for them, but that's it in a nutshell.