Rear diff rebuild

Hi everyone
New to the forum and need some help. Have howling ( turbine type) sound from rear end. Shop says it's rear diff. He says put a used rear axle assembly on but they all have 70k miles+. Is that the route to go or rebuild and get new parts? What is average cost. Also is the jeep drivable while I'm deciding? Can anything happen while on the road?
Thanks
Michele

Also how do I know which diff I have? 2002 limited 3.7. I did the jeep.com request haven't heard anything back yet

Look at the rear diff,if the bottom is flat you have the 8.25,if it's round it's the D35.Look at about $700-$1000 for a complete rear diff rebuild at most shops.

Rear difff

Thanks for the info. So rebuilding is def the way to go rather than swapping a used axle asembly?

oh yeah rebuild for sure
however shop around for a good price and make sure they know what they are doing
the local shop that does gears charges $300 Labor + parts
so basically about 4 hours any more and they dont know what they are doing
also do some web shopping for your parts
most times a "master over haul kit" is about $200 and a Detroit TT is not much more than a stock carrier

My rear axle started really howling at about 50k miles. I took it to a shop around 90k miles for a diagnosis. They agree the rear end needs to be rebuilt; quoted $700-900 depending on what needs to be replaced, this including replacing axle bearings and seals. I haven't had a spare $700-900 laying around so now at 111k miles, still going, still howling. I change the fluid at 10k mile intervals and look for pieces and chunks. So far so good, but I know my time is running out. The howl is getting louder than I can turn up the stereo.
I found a used axle at the jeep junkyard in Sacramento, but they wanted $650 for it, as is condition. Didn't seem worth it.

I have the same noise coming from the rear. One shop said it was the rear diff, probably a pinion bearing but wanted $1200 to start. Price went up from there.

Took it to another shop a few months later to have them look at it, because they quoted me $600. He opened it up, couldn't find anything wrong. I really pressed him and he said, "Hey, I'd love to charge you $600 (or more) but we can't find anything in there."


Then he asked me how long I had been driving on it with the sound? I told him I had put about 12000 on it. He said that there wa no way I had a bad bearing that was making the same noise after putting 12,000 miles on it. He said the noise would have gotten way worse.

So I still have the noise, but have never found it. And I have isolated tire noise I have, so I know it's not that.

I've been told there's one other possibility, by a couple friends that frequent other forums - that it's not a problem with the rear diff, but a problem with the rear suspension - more specifically, with sound isolation for the rear diff.

I've got similar symptoms - around 50 to 52K miles, started getting what was either driveline or tire noise faintly at highway speeds. It's gotten progressively louder such that it's faintly audible at street speeds, and quite audible at highway speeds.

I've went thru nearly the whole range of possibilities - front end alignment, rotating and balancing tires, pulling the front driveshaft, new tires (because the first shop that did an alignment effed it up and wore out two tires). Everything kept pointing to the rear diff or driveshaft.

But there is no vibration or other problems - just noise. I've driven other vehicles over the years that had a problem with the driveshaft or rear diff, and believe me, you would KNOW that something was out of whack - as the one gent said, you wouldn't make it 12K miles after the noise started if there was something seriously fubar with the diff.

My friends pointed me in the direction of the balljoint and bushings in the rear suspension being worn out - transmitting any noise from the rear diff directly into the cab. More specifically, the rear upper suspension arm - at the point of the "V", it's attached directly to the top of the diff by a balljoint, and to the body out at the ends of either arm via rubber bushings. If the balljoint and bushings go south, you've got a direct path for any noise from the diff to be transmitted directly to the cabin - like sitting inside an echo chamber.

From what I've checked, a new balljoint will run from $40 to $60 depending on which brand you get, and the two rubber bushings $15 to $20 each.

Might be worth giving this a shot to get rid of the noise - if it works, that beats paying $500 to $1000 to get the rear diff rebuilt. Besides the fact that if that balljoint and bushings are worn out, your rear suspension isn't working correctly and can cause other problems such as handling and unusual tire wear.