242 to 231 swap
 

How would I go about swapping a 231 Tcase into my 96 ZJ? It has a 242 case in it now, I would like a 231. Would I need to find a case out of a 96 XJ, do I need to modify my output shaft or driveshaft at all? Would I need to swap my speedo gear and linkage?

It depends on which engine you have in your ZJ. If it's a 4.0, I see no problems since the 231 came in the XJ and they never had a V8 AFAIK. The speedo gear and linkage should be the same, but IDK about the driveshaft.

Oh wait....The transmissions are different. Your ZJ has a 42re and the XJ has the AW4. IDK if the input shafts are the same. Oh well, I tried.

Dave, what is the difference between the 42re and AW4?

All ZJ 242's are .840" and 23 spline, find a donor 231 that matches. I don't recall the years from an XJ offhand.

You'll need the 231 shifter gate and bezel as well as linkage. 231 ZJ bezels are rare.

Check out jeepforum.com/forum/f13/transfer-case-swap-info-np249-np231-np242-685644/. It should give you all the input shaft details.

Maybe not! I just checked and all the photos are locked by Photobucket! Looks like a 96-01 XJ 231 will fit.

I Did this swap with no issues the same year tcase, I did a 249 to a 242 to a 231 over the last while. Key is that the inputs are the same spline and input length. There is a chart on jeep forum that is pasted all over the web with what years had which input. I also had no issues with the shift linkages going between cases.