zackcj7 Posted February 21, 2013 Share Posted February 21, 2013 I apologize in advance if this topic has already been beat to death. I searched but couldn't find any clear answers. I have am '86 MJ with a AX4 and a NP207. I would like to swap the NP207 for a NP231. From what I have read my NP207 should have a 21 spline input shaft since it's mated to an AX4. So I will need a NP231 with a 21 spline input. These should be found on XJs, MJs, and YJs made after '86 with an AX5. I know the front output is different between the NP207 and NP231 so I will need an '87 and up XJ front driveshaft. I also read the shifter is different so i'll need a shifter from a XJ or MJ with a NP231. Am I missing anything? Is the YJ and XJ/MJ NP 231 the same? Link to comment Share on other sites More sharing options...
Eagle Posted February 21, 2013 Share Posted February 21, 2013 The YJ is different. The transfer case shifter in the YJ bolts directly to the t-case rather than using a linkage, the shifter arm is inverted compared to the XJ/MJ version, and the t-case is clocked differently (although that's a function of the transmission rather than the t-case IIRC). Your best source would be an XJ or MJ. Remember you can also use a 231 from a 4.0L with the Peugeot tranny (87 through early 1990). Link to comment Share on other sites More sharing options...
zackcj7 Posted February 21, 2013 Author Share Posted February 21, 2013 So the Peugeot has a 21 spine NP207? That will help finding one. Four cylinder manual XJs are rare around here. Link to comment Share on other sites More sharing options...
misfitmechanic Posted February 21, 2013 Share Posted February 21, 2013 Early ax-15 also had a 21 spline input if I remember right Link to comment Share on other sites More sharing options...
Eagle Posted February 22, 2013 Share Posted February 22, 2013 So the Peugeot has a 21 spine NP207? That will help finding one. Four cylinder manual XJs are rare around here. No, the Peugeot has a 21-spline 231. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted February 22, 2013 Share Posted February 22, 2013 I too was wondering if I should look for a 231 to replace the 207 behind the AX 5 I am going to swap into my truck.... eventually. This is good info. I've swapped the axles in already just waiting for my current clutch to die. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted February 22, 2013 Share Posted February 22, 2013 And here's another question.... are all XJ MJ 21 spline 231s the same? Link to comment Share on other sites More sharing options...
zackcj7 Posted February 22, 2013 Author Share Posted February 22, 2013 No, the Peugeot has a 21-spline 231. Doh, that's what I meant. Link to comment Share on other sites More sharing options...
misfitmechanic Posted February 22, 2013 Share Posted February 22, 2013 Just curious, why are you swapping out the 207? Isn't a 207 and 21 spline 231 essentially the same case? Link to comment Share on other sites More sharing options...
zackcj7 Posted February 22, 2013 Author Share Posted February 22, 2013 Just curious, why are you swapping out the 207? Isn't a 207 and 21 spline 231 essentially the same case? 231 is stronger. Plus I plan to do a doubler down the road. My MJ will mostly be a trail rig. Link to comment Share on other sites More sharing options...
Eagle Posted February 22, 2013 Share Posted February 22, 2013 Plus the 207 has a low ratio of 2.6x and the 231 is 2.72:1. Slightly better crawl ratio. And better oiling. Link to comment Share on other sites More sharing options...
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