Driveline vibration and output seal?
 

Just picked up an 82 sr5 and I noticed around 45 mph i start feeling vibration from the rear. My first thought was that it was the u-joints. I haven't checked them yet but I figured I would ask before I did so I can check for anything else.

It has a 3-inch lift on 33's. I dont think that 3 inches would be enough to disrupt the pinion angle enough for it to matter but I could be wrong? If anyone has any insight on things I should check for let me know.

Also, the output shaft seal on the transfer case has a slight leak, I've never replaced one before. Would be nice to have a tutorial or something if someone can point me in the right direction? Does the fsm cover this?

Thanks in advance!

The vibe sounds like a ujoint. Try to wiggle it. There should be no play in the joint. Ive had joints seem fine but I replaced them anyway and the vibes went away. As for the lift maybe being the cause. How is your pinion angle?

The output seal on the tcase is pretty straight forward. Remove the 4 bolts holding the drive shaft on. When the shaft is off you will see a large stake nut, Im not sure what size it is off hand maybe 24mm.

Remove the stake nut and pull off the flange and you will see the seal. Pull the seal out using whatever means necessary and stick your new one in. Bolt it all back together and you're done.

Some people replace the stake nut and its a good idea to do so. I however don't because Im lazy and so far have had no issues with one backing off.

And while you're at it, you can take pictures and write a tutorial :)

If you do enough searching, you may be able to find one that was already written. I'm pretty sure I found something with photos when I was looking into replacing mine. It really is pretty easy. Hardest part, from what I remember, was finding a way to keep the shaft from spinning when you're trying to get the nut off, and tightened back on.

From experience last week! Ill chime in, check to see your 3rd member in the front it secure, make sure the bolt is tight it's a 19 I believe maye 22 I can't remember off the top of my head, and it sounds alot like your u joint. Mine was gone after the front 3rd member dropped and destroyed it in my 89 ADD p/u.

Replace the front u joint
It can't hurt i only paid 40$ parts and install.
All my vibrations are gone, it feels like a whole new truck now!

Hope this helps you out