so acouple years ago i was traveling back from a wild weekend in riggins and hit a rock with my rear end. checked everything out underneath and it all looked ok till the next morning. there was a substantial puddle underneath. i replaced seal after seal where the driveline hooks up and to this day it continues to leak. so the question is, is there anyway i could have tweaked the rearend enough to make that seal keep blowing out and is there anyway to find out or measure if it did move?? any help thanks

which seal. there are 3 plus diff cover.

One thing you might want to check is your axle vent tube/hole to make sure its not plugged. On my 96 D80 the vent is on the drivers side axle tube integrated with a brake line fitting thing that sits on the axle tube.The pinion seal on my axle was leaking about a year ago and I was about to have it replaced but then I was told that if the vent tube is clogged some pressure will build up in the axle and push oil out the pinion seal, so I cleaned my axle vent out and I haven't had any trouble with it leaking since then.

i didnt catch the driveline part of his post. What bjytech stated is true, another thing to to consider is the wear on the yoke shaft. The original seal will wear a groove in the yoke shaft where this seal sits and when you replace it, if the new seal sits in the same spot it will leak if the groove is severe. I had mine done a few months ago and the new seal sat ahead of the old wear groove and no leaks.if the breather hose isnt the issue, you will probably need to have the yoke pulled off and inspected. if bad enough it will need replaced with another seal. Before all this too you can check for pinion housing cracks that could be causing the leak. hopeully this isnt the case.good luck and post if ya need anything!