Been to 2 shops, no one knows the answer. Noise and vibration, tire wear pattern.

[AndrzejConner]

My 98 had that happening. My rear spring ubolts we're stretched/worn out enough that with different weight my rear axle would wrap differently. I was so frustrated trying to figure it out that I was under it one day with a pry pushing and pulling everything. I watched my springs move as the bolts stretched. Good luck.

 

[KRStone]

Thank you all for the posts.
My tire wear is unexplained.
However, I took my truck into a shop and the pinion, and side carrier bearings were all potted and coming apart. $700 and back on the road (ouch!)

 

[Matt42]

My 98 had that happening. My rear spring ubolts we're stretched/worn out enough that with different weight my rear axle would wrap differently. I was so frustrated trying to figure it out that I was under it one day with a pry pushing and pulling everything. I watched my springs move as the bolts stretched. Good luck.

This is what I would have suggested looking at. Did the work you had done solve the problem?

 

[AndrzejConner]

This is what I would have suggested looking at. Did the work you had done solve the problem?

Yes. For me, that is what my issue was. 4 new rear leaf spring to axle u-bolts and I also replaced the rear spring shackles and hardware also as they were pretty pooched as well. Those large u-bolts are supposed to be 9/16" diameter, the ones I removed were as thin as 3/16" right where they pass through the "cup" that sits under the rear axle tubes. They just slowly rotted away from 20 years of Massachusetts road salt and whatnot eating them away. I noticed the odd tire wear when I was in North Carolina with a few thousand pounds in the bed and an 18' tongue pull call trailer at around another 8k pounds behind me. Luckily, I caught the funny wear pattern at a truck stop while fueling up and giving the truck a quick walk around. I went investigating later when we stopped for the night and was thoroughly surprised to find the bolts stretching when I got the pry bar in there. I could see them move a good 1/4" or more just from poking around with the bar, I can just imagine that at the right bump in the road with the trailer and truck weight how much they were really moving. My truck has lived in Massachusetts since new so these things you can't avoid, and it's not all rotten out. Salt and debris just find their way into the smallest of places.

So, many different things can cause similar symptoms. I wanted to share mine so that you other guys that come from areas with salt treated roads will not end up like me and changing those parts out in a hotel parking lot in one night with only hand tools. I carry a small collection of tools and equipment with me for road repairs etc but this certainly tested my abilities. I don't recommend attempting it without air and oxy/act. Why did it do it myself? I was quoted around $2k from local shops to do the work which would have included rear spring packs. Yeah, really! Also, I couldn't wait 3-4 days even if I was made of money.

Check your equipment over well before you hit the road and then always give quick visual inspections whenever you stop for fuel, food, etc. This wasn't the first issue I caught from doing so but it was definitely the most serious. I broke two ubolts by hand with a short breaker bar when disassembling. That could have been the next pothole I hit or even the next tight turn I made.