You need a selection of various thickness pinion shims that will fit in between thw front pinion bearing and the new pinion crush sleeve replacement spacer. On used bearings I would shoot for between 12 to 18 INCH lbs rotational torque (test it both ways )with the pinion yoke and pinion gear pointed straight up. Make sure there is no dirt or debris in the bearings or races I use a small amount of the gear oil I'm going to run in that third members as a lube, it doesn't need to be drowned in lube, a light coating will do for set up purposes Once you get the pinion bearing preload set reassemble the carrier and set both the carrier bearing preload and the back lash(make sure and check the backlash in 3 or 4 places around the ring gear to make sure that it is on straight and not cocked sideways on the posi unit, it shouldn't vary more than .0015 max Now get to work