When you get the yoke off you will need to remove the flange. It has 5 bolts. The seal is replaced from the back side the flange. You don't have to check the preload. When you tighten the pinion nut it will go back to the position it was. If there is looseness in the pinion brgs after tightening the nut, then you have a bad brg.
When putting the flange back on there is a thick cork gasket that goes between it & the housing. It takes up the gap between the flange & housing. I you can't find one you can use a thick bead of RTV.
George
