12 bolt pinion seal thowing more than leaking?

[1980]

Hey Guys,
My '79 rear is throwing oil when I'm moving, mostly up on the bottom of the bed.
Doesn't leak on the ground or leave a puddle. I'm guessing this is the seal going out.
I read the searched posts and think I'll go ahead and try to replace just the seal.
Any thoughts on this before I cause myself more headaches?

Thanks,

 

[Hogback Fabrication]

Make sure there is no play in the pinion bearings, a lot of the time (especially on a truck 12 bolt) the pinion seal starts leaking because the pinion bearings are toast.

 

[chulisohombre]

i broke 2 12 bolts and was mostly due to the pinion movement.lost all the fluid on the first and ring gear blew through the cover on the second one.if the pinion gets loose at all it will wobble and take out the seal first.it has a set preload that the pinion has to be set back at after replacing the seal.i believe it was 12 inch pounds to rotate the pinion.as long as you snug the nut back down and put at least 20 ft lbs on the pinion nut it should stay good.thats as long as there is no wobble in the bearings.