You unbolt the Stock shackle turn it 90°, bolt the lift bracket to it through the 2 holes, then bolt the horizontal part if the lift bracket back into the factory holes, Think I did a little redrilling there to make it stronger where it bolts up to the sub frame, 2 bolt mount there too. Can put a reinforcement plate up inside the box section of the sub frame for more strength too.
Orrrrr . . . Just put on Monroe Max airlift shocks from Rock Auto with your factory mounted leaf springs. That works too, they give a nice ride and lots of adjustability if hauling around more people.