It's a LS rear gear.

 

Axle code on the door plate is 19, which I believe is the 3.55 non-limited slip. Correct me if I'm wrong.

 

Shooting in the dark, but would crap fluid in the rear diff cause this? Maybe changing it could be the culprit?


-Matt

 

If you have 161k and have never changed the rear lube, it sure wouldn't hurt. 75W-140 synthetic, and you don't want modifier in a non-LS.

 

Change it anyway. Use the good stuff. Also, mark your shaft, then pull it. Clean the slip yoke with brake cleaner. Apply a thin coat of Teflon grease. Reassemble. Make absolutely sure your breather is clear. It's service, so it should be done anyway regardless. Don't ignore, you may be surprised of the out come.

 

My money says he has the stock chrome wheels.

 

Why not go back to diagnostic attempts to get a lead on where the issue orginates from.
1. What happens if you kick it to neutral at 65 mph?
2. What does it do on upshifting?
3. What happens when you brake?
4. Why is there tire wear? Must be an issue!.
5. Front end alignment? mutiple worn parts etc!
6 Is a rim showimg obvious signs of being bent?
7. What happens if you raise the rear up off the ground and spin it in drive? Does the truck shake?
8. Is there any signs of brake disc tight spots?
Some where here you have to see an issue.

 

I do not, but why were you thinking so? Is there a known problem with them or something?

 

Well, had them do it at Jiffy Lube about 30K miles ago, but come to find, that I'm pretty sure that Jiffy Lube doesn't do half of the services they charge you for. Right after they supposedly changed it, I had it at my then regular mechanic for brake pads and he routinely checks all the fluids of anything he works on and told me that the rear diff was almost empty! So he topped it off, but who knows what they did or what he added to it. *sigh* So it probably wouldn't hurt to do this one myself and see what it looks like in there.

I hate that I have no faith in anyone working on my vehicle. If I didn't do it myself, and plenty of things are beyond my knowledge, tools, and available time to do myself, I've had a very difficult time trusting the work of others.

 

You just gonna use the drain plug or your gonna pop the back of the case off? Personally, I would open it up and take a look at the internals and make sure everything looks good.


-Matt

 

The chrome wheels for the YM 2001 and first 4 months production of the 2002 trucks were faulty and weak. They were noted for vibrations and odd tire wear. I had mine replaced by Ford on the 02 I had. A friend had one break at a mall parking lot and by the time they got it loaded on a wrecker, the other three were cracked. Ford replaced his as well.

I'd jack the thing up and get all of the rotating mass running and give it a good look. Most any vibration under weight load is going to show up much better with zero load. You'll also be able to hear any noises that could lead you to the issue. Does the rear axle get hot after a run on the hiway? You can put yer hand on the wheel to check for temp but that can also indicate a dragging brake which can also come to you as a vibration.

 

There is no drain plug on a stock rear diff cover.

 

My bad. Thoght I had seen one under there. Must have been our Jeep or something. Thanks for correcting me.


-Matt

 

Good to know, -haven't heard of that one.

 

Not to add to your plate....just another thought on the source of this vibration.

Has the tranny mount/s been checked and or U-joints?