here are some notes which helped when I installed my own SS1.2 lift and SS adjustable PHB:
jack up the rear axle slightly to ensure the bolts slip right out of the PHB -
you should not pound them out – just fiddle with your floor jack to finesse out the bolts
PHB length (for my 3" lift) = 37-5/16" center-to-center
then finish off the adjustable PHB installation by tightening the jab nuts on each side
after installing your lift (and while the rear end is still off the ground), loosen all 8 bolts securing the rear links (upper and lower); reset those at ride height once everything is relaxed and then re-torque them once the rear tires are sitting on level ground again
get an alignment due to the lift