Not hard at all. They send pretty good instructions.
You'll need a spring compressor for the RF spring. Jack up under the axle. Put jack stands under the frame. Remove tires, Lower on to stands, disconnect shocks and sway bar, lower axle. Remove LF spring, remove isolater. Install spacer, then isolater, then spring. I had to stand on axle to get everything to go in. On the RF you'll need a spring compressor to get that spring back in. Make sure you get the pigtail of the spring in its pocket. They'll turn by hand with the axle hanging. Jack back up, install shocks, and reattach sway bar. The rear is the same but you'll won't need a compressor. On the rear axle shock mount remove the bolt as the nut is attached to the bracket. Some companys suggest you put the rear spacers on the axle, others say on top of the spring. But everybody here says to put them on top of the springs. I did.