rebuilding a Dana 70... need help

[AVZ]

Hello, I originally have been chasing ghosts in my front end trying to find what is causing aall the heavy grinding and popping I could feel through the steering wheel. The problem only happens if I turn the wheel left or right but was fine straight. If I put it neutral while taking a turn then there is no problem. Also, if I tap throttle and let off I can hear a clunk. Also chunks when going in reverse

I recently had a friend creep the truck around a parking lot with the wheels turned as I felt each wheel for vvibratios. Without a doubt the problem is in the rear axle. I can visually see the wheels "twitching" which I felt as popping in the steering wheel. Can anybody pinpoint from this description what specifically needs fixing or would I be better of with a complete rear end rebuild? Where is the best bang for the buck rebuild kits? The 93 w250 had a Dana 70, right? Would it be overly complicated to go from the 4.10 to say a 3.73 gear while I'm at it? Thinking this might be a good time to improve the mpgs and highway speeds. If there is a writeup about this please share a link especially if there is a complete part's list for the rebuild.

[PToombs]

Sounds like the limited slip isn't slipping. Change the oil and look at things while the cover is off, especially check for excess metal in there. Put in some new oil and LS additive then go for a drive, if that was all that's wrong it should stop popping and grinding.

[dazedandconfused]

Someone could have rebuilt the limited slip and set it up "tight" which is causing what your explaining.

[AVZ]

Ok.. .changed the Gear oil and added additive... IT WORKED!! Grinding has gone away. Still slams in reverse and occasionally into second or 3rd gear

[dpuckett]

The slamming/thunking is wear somewhere in your driveline. I'm surprised yet happy for you that an oil change helped the grabbing in the rear. I've not been so fortunate.

Check u-joints and spider gear for slack.