I think that actually may help - Just my .02, other opinions may differ. By increasing the height of the rear it changes the fulcrum point. Also, if you have the A/T tires and not the LT currently, you may want to try a regular LT first before going to 10 ply which is heavier.I was theorizing that if I raised the rear under load (functionally stiffing spring rate) and put more weight onto the front that the tail wouldn't wag the dog quite as much. I also thought combining this with E-rated 10 ply tires would also aid in reducing the squirrely-ness.
I've also found that riding with more weight redistributed to the bed (not to exceed capacity, I scaled mine) helps keep the truck planted