best to stick with the ax5. means no modification or adaptation. or...
you can use the trans from the later TJ with the 2.4L known as the NV1500 from years '03 and up...or it might be from '04. the bell housing mounts up to the 2.5L but you will have to run a different hydraulic line for the external slave that the NV1500 runs. also, i believe the output spline count is 23 whereas the ax5 is 21, therefor your t-case will need to accommodate this by swapping the input gear or sourcing a t-case from the 4.0L jeeps.
i also heard that some dodge dakotas share a common transmission relative to the ax5 so you might want to look into that.
I looked into all that recently, and just ended up getting my AX5 rebuilt, it wasn't worth all the cost and trouble to me. And I didn't want a used one, as they are inherently weak. As asked, what's wrong with yours?
i agree with Air and Digger. especially when a used ax5 tranny are easy to come by, you are still better off having it rebuilt. the shops usually put a warranty on it anyway. the problem with ax5s is that they are so weak that if you come across a used one it might already have problems. stay away from the later YJ ax5s though, they are particular about the oil you put in them.
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