NP231 Clunk when starting from dead stop
 

I recently picked my Cherokee up for $100. $5000+ later, it's got a new motor, has a lift and tires, and is on the road again.

Now, every time I start from a dead stop, there's a horrible clunk/rattle coming from the back-end. I ripped the brakes, and rear diff apart and made sure everything was clean,tight, and proper, replaced the wheel bearings and u-joints, but can't find anything that appears to make the clunk.

One thing I did notice while crawling underneath is there is a lot of slop (backlash) from the rear output shaft/yoke on the transfer case. Does anyone know if this is common in an NP231J?

The noise stops almost immediately once I get up to speed, but happens everytime I start from a dead stop.

sounds like a streched chain to me , very common in the 231/242 transfer cases.

But easy to rebuild.

Thanks, Amigos! Do you think it would be easier to rebuild or just replace? I have access to a second unit, but it's a few months out (my brother just got a 96 XJ and is planning to part out his 89 MJ but that won't happen for a few months).

I would rebuild it then you know whats there and that it is in good condition. Save your brothers for a spare. I have a spare sitting under a tarp behind my workshop and can slap it in with in a few minutes if needed.