I currently have a NP231 TC (23 spline) but I need to convert it to a (21 spline). I know there is a conversion kit to convert from the 21 spline to the 23 spline, but in this case I need the opposite.

Does anyone know where or how to change these spline count??

 

You can buy the input shafts. You just need to buy a 21 spline input shaft, pull the front planetaries out and swap it out. I don't know how cheap they are, but I bet somewhere like Advanced adapters sells them.

 

The best thing to do is try and measure the outer shaft diameter, and the length of the input. There are several different ones.

In order to change this piece you have to totally disassemble your t-case. You will need a good set of snap ring pliers. If you can get me a measurement.. I think I have a 21 spline output in my garage I wil sell.

 

You would probably be better off trading someone straight up, most people want the 23.
...but, you can change out the input planetary with out too much more work than installing an SYE.

 

So far,

Ive removed the np207 transfer. Ive check to make sure I can still use the existing rear driveshaft, and Im good there.

I order a 21 spline input gear from Chrysler, which cost about $70.00. So while im waiting on that Im gonna check out some youtube videos for dismantling the np231.

Ill keep you posted on how everything goes together. One more thing, the np231 is out of an 91 XJ so all the bolt patterns look like there gonna match up to my AX5 5speed tranny.

Now I know why there are so many 86 cherokees on craigslist, cuz they're not worth there weight in scrap metal . Oh well, keep livin and learn'n

 

Novac has all the info and parts you need.

 

Hey, I have a 21 spline count shaft and need the 23, do you want to trade? lol
Take a picture of the shaft and we can see if they are the same length out of the case. They are easy to take apart and are like a Lego set. You just need those heavy duty snap ring pliers. I think they sell them at Pep Boys. They kind of look like a duck bill.

Let me know, we can just swap.
I bought a 93 AW4 trans "23 Spline count" and my t-case is 21. I bought all this stuff to convert my 2WD XJ to 4WD.