I have had a vibration for a while, so I replaced the universals and that did not fix it. I think the rear end is to blame. The vibration will start around 30 and get worse to 45 and then lesson a little.
These are the exact same symptoms that my car had when I replace my existing driveshaft with one from an 81'. My car is an 84 se.

I was under the car today, looking at it, when I noticed if i bump the driveshaft the rearend makes a clunk noise. It sounds like something is loose in there. What could it be, and what do I need to rebuild.
My lsd still works great, I left two even black streaks in my driveway.

 

Could be just loose bolts (driveshaft, watts link, etc etc), or uneven wear on the tires, I am getting the same thing, but mine happens when I let off the throtle and coast only from 30 on, and its not coming from the engine, cause if I rev it it stays the same doesn't get any worse or better. You may just have to play around checking bolts.

No better place than to, then in your OWN STINKING driveway

 

check the spring mounts, they may be rusting

 

Had a similar deal with mine. Replaced the U-joints and it got better for awhile, then came back. Ended up replacing the pinion bearing and its been fine since. IO guess the vibration from the bad U-joints shortened the life of the bearing.

 

I know it is not the wheel, because I jacked the rear of the car up, took the wheels off and ran it up to about 45 and it still vibrated.

CrazyJoe12a
Where did you buy your pinion bearing?
and what else should I replace.
Should replaceing the pinion bearing also stop the rear end whinning, or do I need to also replace the pinion depth spacers?
thanks

 

I bought both new pinion bearings from VB. I reused the distance piece. Just be careful not to torque the nut down too hard, I think it only calls for like 90-120 ft.lbs.

 

Should I replace anything else in the diff while I am in there. Do you replace the carrier bearings for the axle also.
I just want to make sure that I can stop the whinning while I have the rear end apart.

 

The carrier bearings have to be pressed on/off. But while you've got it apart, and if you have the money, might as well go ahead and do it.