The advice from 65sporty was spot-on, and yes, the seal is easy to change once you get that pinion nut off and remove the yoke. And yes, for our world of generally "low performance" cars (no drag racing shock loads!), his method of rotating the pinion back and forth to get a feel for the amount of preload/slop/lash BEFORE you loosen the nut (it could be measured with a dial indicator, too) is a reasonable method to match the preload on the crush sleeve when you go to tighten it back up. Or, make a careful pip mark on the yoke and the nut and the housing (so they all line up perfectly, somehow), and re-torque that nut to the pip mark assuming you put the yoke back on to the exact splines from where your removed it. Thus all the pip or sharp cold chisel marks I mentioned that allow you to exactly reassemble it as you found it. Count spines, take pics, etc. Do this, and the crush sleeve will do just fine for a long, long time.
