The sway bar will help to reduce wheel hop with a pickup truck and result in a much smoother ride. It will not fix your sway problems with a load in the bed. The problem is that more than half the load weight is on side of the rear wheels and the leaf springs are not adequate to deal with the weight.
Fix the load capacity problem with SuperSprings and the problem will be greatly reduced. A side benefit is that your shocks (dampeners) will last much longer. With coil rear springs your options are more limited and it may take special air bags to increase the load support.
I added SuperSprings to my 2500 and it was able to carry a 3700 lb slide-in camper with ease. I added the Hellwig Big Wig and rear wheel hop was greatly reduced, especially if turning and hitting a bump in the road. The sway bar transfers the impact at one wheel to the opposite wheel which is a negative in a sports coupe but a big positive with a pickup truck.