Long story short, my brother's 01 TJ needed a transfer case. Since his has an AX5, the input shaft has 21 splines. All I could find locally was a 95 XJ 231, which has a 23 spline input. I pulled the XJ unit apart and replaced the input shaft with his original 21 spline input, and swapped the extension housing.

Now his output shaft has about 1/4" of end play. I replaced all the bearings and the chain. I followed the FSM to the letter, and (I'll even beat my own drum here) I'm even ASE certified in all areas. Once it was all together and siliconed, I went to install it and noticed the shaft end play and got a little concerned. Any ideas? Why would swapping the extension housing change output shaft end play? Or is it because of the input shaft?

I'm kind of at a loss here. All I can find is that the input shafts are different, but I already knew that. Does the output shaft have to match the extension housing too?

 

Do the different tail housings retain the output bearing differently? Snap ring versus the tail housing holding it in?

 

Ok so I figured it out, followed by utter disappointment.

First off, after about 30 minutes of drinking about it, I noticed the snap ring I didn't install. Had to remove the output shaft seal, installed the snap ring, installed a new seal, and away I went. Did a 3 hour drive to his house and I go to put it in. I get there and now he now asks me to install a rear main seal (2.5 TJ, so it's one piece), and replace the clutch and flywheel. Jeez man. "While you're there" sorta thing I guess. Ok, not a huge deal. Just a little extra time.

I get all that sorted out and now it's time for a test drive. Man, everything sounds great. Clutch is perfect, no transfer case noise, it even shifts smooth from 2H to 4L and back. It's MINT.

Get it home and I see ATF puking out the back of the transfer case.

Moral of the story is: Extension housings DON'T interchange. So I'm back home again (3 hours away) and I am now swapping in the output shaft to make it match the extension housing. The newer style extension housing that seals against the shaft is longer. The older style shaft doesn't have a place for the new style seal to ride. It just looks like it ALMOST does, but it doesn't. Trust me. There's nothing you can do. Just don't try to swap extension housings and you'll be good.

 

Yeap!
Been down this road once before.

 

Someone before we bought our Jeep xj sheared off the bolt to the output shaft.

 

You mean the front output shaft? Because there's no bolt on the rear output shaft unless it's been modified for a "hack and tap" slip yoke eliminator.