Originally Posted by Summers22

Lowering shackles are the same for any leaf spring. Jack up the rear by the differential as high as you can, place stands on the frame rails in front of the rear wheels, remove your wheels and let the jack down as far as it will go, but leave the jack under the dif, then remove the bottom bolt in the spring hanger (on my truck the spare had to be lowered, 07 FX2), then remove the top bolt (as mentioned the top bolt is hard to get out) then its reverse process to install new shackles. Tighten the 4 bolts snuggly but not fully, install your tires, lower the truck to the ground torque your wheel lugnuts, then torque the 4 bolts.