[Guest]

Will an NP231 bolt right in to my 87 YJ auto, in place of the NP207 it has now?

 

[027]

Well to tell you the truth I'm not 100% sure but I think all the auto's on the Jeeps have the 23 spline.

I know the 207 behind the BA10/5 for 87 has the spline count at 21.

This said you should be able to bolt the 231 in place of the 207 behind an auto. Spline count is the only issue as bolt up is identicle.

Hope this has helped some.
The bottom line is spline count 21 on NP207 and 23 on NP231, auto is the exception,,,,, I think.

 

[Dirt Dog]

I don't know for sure either. But I do know that they work when doing this same thing on cherokee's (both) with autos. I have seen it done several times. My local tranny shop won't even mess with a 207. They just throw a used 231 in it. They told me it was a "bolt in" with a few small shifter linkage mods.

***But this info was for a cherokee and not a wrangler AND I have never done it. It's just what I've been told****

 

[NIX]

'87 And '88 cherokees have BA manual trannys (mine does, unfortunately) and a 231 X-case with 21 splines, af far as I know

 

[JEEPININMEXICO]

I bolted in directly a late 87 NP231 that I ordered from a yard in Maine. Before installing I put on a short shaft output for the CV drive shaft.

 

[NIX]

Check this:

http://home.earthlink.net/~jeepcherokee1/Transmission%20and%20Transfer%20Case/Transmission%20Information.htm

I quess you can conclude there are 231's with 21 aswell 23 splines. No matter if they are from auto's or manuals.