Anyone know the best place to look for 231 rebuilds? I dont have a problem with shifting or 4WH/4WL, but I put it up on jack stands and I surely have a scraping/grinding sound comeing out the T-case. You can hear it coasting, driving in 2W or 4W. I'm parking the Jeep until I can get it repaired.

I'd look at rockauto.com

Pep Boys said 753.00 + 300 core
Autozone said 599.99 + 300 core (21 spline) and 639.00 + 300 core (23 spine). Guess I have to pull it to find the spline count.
Rockauto w/o Motor; 23 spline front input 27 spline slip rear two piece tail housing, NP231J $666.79 + $350.00 core

Guess I need 23: NP231 transfer cases come with either a 21 or 23 spline female input. The 21 spline shaft is frequently found in 4 cylinder applications and the 2.8L V6, While 4.0L 6 cylinder and 8 cylinder applications always used the 23 spline input shaft.

Could it just be the bearing and seal?

the chain is worn. chain is under $100 from jeep. buy that, tear it apart, buy a new $13 filter for it, and maybe buy a new set of nylon shift fork bushings.

I wouldn't think chains make that much noise. I only think I've head the chain skip one in a real hole I was in. Maybe the thing is dry inside. I'll probably need to take it down and have a look before ordering a rebuilt unit.

Yeah you can check the fluid level by taking out the top plug and sticking your finger in there. New chain is pretty cheap and could definitely be the culprit

I just rebuilt mine a couple weeks ago. The snap ring on the back of the synchro hub fell off and the little keepers that keep the hug together fell out. The case still shifted and worked fine. But it also made a grinding sound. It WAS the chain. The case had run low on ATF and the chain dried up. I did a full rebuild myself, but replacing the chain is what fixed the noise.

That really helps. Thanks for the info and I'll look more into the snap ring and fluid level to see if mine is in the same boat.

Thanks, I had too much snow on the ground to get up under it today. I should dry out here next week.

The chain does not turn while the T case is in 2 wheel drive, only 4WD, so if you have a scraping sound in 2WD, there is another problem inside the T case.

The 231 is really simple. The only things that can fail are a bearing, the chain, or the snap rings on the synchro hub. I would check the fluid level first. Second, if you are capable, take the back half of the case off and look in there. If there is a major problem, you will see it immediately. This is what came out of mine. The first pic is the keepers that came out and allll the metal filings that were piled up on the magnet, along with all the little nylon mode fork bushings. And the last pic is the snapring that got mangled up in the chain.

The scraping was in 2WD. So maybe it is bearings of something. I'm not looking forward to seeing what is inside

If is the bearing, do you need to tear it all down?

Whats rotating in 2wd is the planetaries, the 2 inner bearings inside the drive sprocket for the chain, and the output bearing. Id tear off the *** half and look inside.

Any chain stretches eventually. A 231 chain is no different. if you ever open the case, replace the chain.