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NP231j

Pgw1995

NAXJA Forum User
Location
Arkansas
Hey everyone, I have a 91 np231 transfer case and a 2000 AW4 transmission. Will this work? Long story on why everything is mismatched but anyhow. Someone must have upgraded because the transfer case is 23 spline already, but I have heard something about the spline pitch being different between early and late model 231’s? How can I check that out? Also, I no I’m going to have an issue with the speed sensor in the 231. Is there a kit to swap it over to the electronic so my TCU will know what is going on? Thanks in advance!!!
 
Your 1991 xfer case would have been a 23-spline already and will bolt up to the 2000 AW4 without issue. Splines generally don't have a pitch. I think that was a reference to the internal section of the input gear that changed and only an issue if you're swapping parts between xfer cases.

https://www.novak-adapt.com/knowledge/np-nvg-input-gears/


As for the speedo, you just need the sensor (black unit below). It plugs into the same place and instead of driving a cable it drives the electronic sensor. You'll need to swap over the plastic gear (green in the picture, possibly different color on yours) from your cable setup to the electronic sensor.
231-SYE-91.jpg
 
Your 1991 xfer case would have been a 23-spline already and will bolt up to the 2000 AW4 without issue. Splines generally don't have a pitch. I think that was a reference to the internal section of the input gear that changed and only an issue if you're swapping parts between xfer cases.

https://www.novak-adapt.com/knowledge/np-nvg-input-gears/


As for the speedo, you just need the sensor (black unit below). It plugs into the same place and instead of driving a cable it drives the electronic sensor. You'll need to swap over the plastic gear (green in the picture, possibly different color on yours) from your cable setup to the electronic sensor.
231-SYE-91.jpg



Thank you very much lawsoncl. Since I bought this Jeep and started doing upgrades I have found out a lot. Luckily I haven’t had any CEL from the motor, (all transmission) but it’s a 98 Cherokee, they installed 91 4.0, AW4, and np231. The ECM and TCU are still 98. I am happy with the 4.0, only because it has the best head Jeep ever had (just my opinion) as long as I don’t uncover engine electrical problems after I installed the right transmission. Thanks a lot, you have been great help!!


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