Calvert did his R&D for CalTracs on a 4-speed Super Stock CJ Mustang w/ multi-leaf springs that were flatter & way stiffer than normal... I'd be surprised if those things barely flexed under load.

CalTracs and SS springs "fight" each other, unless you Band-Aid the sh!t outta the combination like IIRC Tony R (n2Omstr) did for a while.

I ran CalTracs w/ basic multi-leaf springs when I first tried them, but I pulled the SS springs off first. Too many people had already complained about that combination. I eventually swapped to Calvert's mono-leafs, which did work better for me.