I've searched and all I find is rear 94-98 zj swaps but nothing saying don't use 99 wj parts for the rear conversion.

I have a 99 rear axle available for cheap.

What's the deal?

Thank you.

 

Different not pattern on wj. (5x5) XJ is (4.5x5)

You can also use liberty rear disk brakes

 

Yeah, looks like more of a PITA then it's worth. Now bout them library rears or the whole 8.8 disk to disk from an explorer... Possibilities.

 

If you have a Dana 35 the ZJ is a bolt on. The 8.8 will require some work.

 

I just got done putting the 8.8 in my 90 Cherokee. Easy job if you have the tools/skills. Torch the old brackets off (grinder if you don't have a torch). Weld on spring perches and shock mounts. Run brake lines using two pass side explorer hoses and original XJ hose in between them. I used a 20" line and a 40" line from Advance Auto w/ the ends already flared. I didn't change the prop valve. I will do that later when I change the booster and mc. The brakes are about the same as they were with the D35. The 8.8 I used has 4.10 gears and LSD. With the 33s on the Jeep, it puts the final ratio back to stock. Many will say 4.56 is better, but the 4.10s were cheap (came in the axle). I checked my speedo against my GPS, and it is dead nuts. The acceleration is good, no data on mpg yet.

 

I misread & though it said 8.8 discs on a XJ axle.

I have a 8.8 in my Jeep & love it. I would recommend it over a disc brake conversion all day long. But it takes more work than some, including myself, are able to do.
I have 35s with 4.11 gears & it does well on the road. It will take a beating too. Offroad it needs lower gearing but a upgraded t case would fix that.

Sorry to venture off topic.