I have an 02 SD 250 PS 7.3 4X4.
I posted this as a reply on another thread about handling. But, decided I should do my own. I have been searching the past post and so far have come up empty.

This is what I am dealing with right now.
I replaced Ball joints last fall, right side axle u joint and hub locks to manuals all at the same time. I had the wobble of death and I just sort of deal with it. But, a couple nights ago i made a hard tight right hand turn. the truck didn't unwind the wheel as usual and when I unwound it it started steering itself side to side. I couldn't keep up with it. this was very low speed. I stopped and restarted a couple times and it seemed to fix itself. i drove to my destination and checked out the steering parts. I found a bad tie rod end at the pitman arm. I replaced that and drove about 75 miles with one of the best rides I have had in a long time. when I went to make a fast tight left turn onto the expressway it did the same crap. Knowing nothing under there is going to break loose. I drove home with it fighting all the way. It pulls left, then it pulls right and back and forth. It behaves kinda like the steering gear is cam shaped and it just wont settle in to the high spot which is exactly where you need it. I checked everything I could yesterday. All steering arms are tight and well lubed, Ball joints, hubs and lug nuts are all tight.
I have come to the conclusion that I have one of 4 possible issues going on here.
1) Steering box is going bad (I checked auto zone site yesterday for a price. Scary thing. they have it in stock locally. Unless this is a popular part. why would they stock it?)
2) Some type of issue in the steering shaft u joints. ( Haven't checked them yet.)
3) Broken frame somewhere under there. (Nothing I have found so far.)
4) Left side axle u joint binding. ( That's the one I didn't replace.It was in very good condition last fall when i did the ball joints.)
So, If anyone has any input of what else they think could be responsible or maybe seen this before?

 

I Have exact same problem.Some time all is OK and some days it locks it self once or twice a day.
All under my truck is fairly new and no loose that I could detect.
From what I could find for info looks like it's steering box and Red Head is the fix.
Bit pricy but guaranteed to work for long.
Don't spend money on rebuild ones from autozone,napa etc.
Word is Red Head and that's my next move.

 

I found my left u joint is binding. actually its more than Binding. Its Seized. So, I'm Going to replace that and see what I've got when i get done.

 

U-joint would be a problem if you're in 4x4 isn't?

 

Yeah. its a problem locked in or not. Still needs to be free for turning. no matter what.
I just started to take things apart and my brake pad is broke in half. as soon as I relieved pressure half of it fell out.

 

Hmmm? if you're not in 4x4 axles won't turn and U-joints neither so i see no problem
with binding or steering it self from side to side.
Maybe I'm missing something?
just wondering.

 

You are missing the fact that even if the U-joint isnt spinning, It still has to bend when you steer.

 

Mine is free moving in one direction and seized tight on the other. No wonder it was fighting so hard and all was well provided the joint stayed in the right position. but as soon as a tight turn caused the shaft to rotate a little. that was when the tight side started doing the driving and I was along for the ride. LOL.
BTW, This joint was fine last fall when I did the ball joints.
I strongly recommend replacing these axle Joints with grease-able joints when ever ball joints are replaced. I know I should have. Now they have grease fittings and probably will never need to worry about Ball joints or u joints again.

 

Ye, that makes sense stumper1620, would you have part ## please.
I was convinced it's the gearbox.

 

Advanced Auto parts. PN # 5270480 $29.99 Ea. W/Grease fitting.

 

Thanks ,will try that first.