Np231 - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today

Thread Tools

Please support our sponsors and let them know you heard about them on
Old 10-03-2012, 07:37 PM   #1
Hogwrangler89's Avatar
Join Date: Sep 2012
Location: South central florida
Posts: 6

Is every np231 the same? Other than there's a 21 and 23 spline. Is there any electrical upgrades on the new ones? I have a 90 and the transfer case broke. The guy I'm buying one from says his has a plug on it and I don't think mine does?

Hogwrangler89 is offline   Quote
Old 10-03-2012, 08:10 PM   #2
Scooby88's Avatar
Join Date: Jan 2012
Location: Mid Michigan
Posts: 418
Yes I just ran into that issue,

They are both stamped 231J the one on the right is a 21 spline and the one on the left is a 23 spline.

[B]To be continued....

You Don't Buy a Jeep, You Build One.

2009 Chevrolet 3500HD Duramax - 25 Ft gooseneck ready to haul the 1993 YJ, stuck a SBC 350 Transplant that will eventually be a 383 Stroker on 1 tons.
Scooby88 is offline   Quote
Old 10-04-2012, 12:41 AM   #3

WF Supporting Member
jokerchief462's Avatar
Join Date: Apr 2012
Location: North Las Vegas
Posts: 9,695
The newer one have a speed sensor instead of cable driven speedo is hwat i hear. But if you have an SYE no issue or you could just swap the tailcones. Yes 21 and 23 spline difference between the AX4/5 and AX15 trans 4 bangers and 6 bangers.
jokerchief462 is offline   Quote
Old 10-04-2012, 08:09 AM   #4
roadyrob's Avatar
Join Date: Apr 2012
Location: west palm fla
Posts: 1,037
you can just swap your mechanical speedo drive to the newer case. like posted 4 cyl cases have 21 spline , 6 cyl are 23. there was a gear change in the newer cases (94 and up) but thats internal.
roadyrob is offline   Quote

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Download our Mobile App

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 06:27 AM.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC. is not in any way associated with the Chrysler Motors LLC