pinion seal on dana 30...

If you don't tighten the nut properly, you will be shopping for new bearings and a ring and pinion. Some of the links posted by Kevin gloss over this point, "Tighten it down with a socket wrench as not to destroy the crush sleeve." That is certainly good advice, but how? When doing a seal replacement of any type, it is a good idea to think about why the seal might have failed. Sometimes, it is due to worn or loose bearings. If that is the case, then replacing the seal without repairing the real problem is like pissing into the wind. If there is a groove in the pinion yoke, then "maybe" you can polish it out, as one of the web sites suggests, but maybe not. Another site says, "Tighten down the pinion nut until the index marks line up, and replace the driveshaft." Anybody can post to a web site, but considering the damage you can cause, a complete service manual might be a good investment. The Parts Plus site appears to have the best advice, and recommends that you go by the original preload. But what if that was off?

Earle

I had a so called "Jeep' shop replace mine and they destroyed the bearings.

I went to a machine shop for the fix and time will tell, but it seems to be holding together.

I will tear down engines and carbs, but I leave the diffs to 'pros' (I hope).

Mike