You have to unhook the driveshaft from the diff.There is a nut on the yoke you took the driveshaft off.Remove the nut slide the yoke off and pry the seal out.Check the yoke for a groove that could be worn into the yoke.Polish it out with fine emery cloth.Put new seal in.You can use a big socket the same outside diameter as the seal to drive it in.Slide yoke back on and put silicone sealant on the threads of the pionion shaft and on both sides of the washer then put nut on and tighten to around 150 ft/lbs.Very tight if you don't have a torque wrench.Feal for any up and down and in and out play on the yoke and if there isn't any hook drive shaft back up.You're good to go.I have done lots of these without replacing the crush sleave,if this diff even has one,and have not encountered any problems.That's why you check end play and up and down play.

 

Im pretty sure this diff has a crush sleeve for the bearing. You think it will be a problem?

 

Like I said I have done seals without doing crush sleave with no problems.If you do put a new crush sleave in put it in a press and give it a little sqweeze before putting it in,but not too much.Doing that just makes it easier to tighten up the pinion nut because you have started the crushing allready.Just don't sqeeze it too much.If you do after you have the pinion nut tight you will feel a little end play on the yoke.