Jeep Wrangler Forum banner
  • Hey everyone! Enter your ride HERE to be a part of JUNE's Ride of the Month Challenge!

1 - 1 of 1 Posts

56 Posts
Okay guys, looking to collect the pooled wisdom of those on this forum, as I may be attempting something in possibly unexplored territory.


When I first got my 5spd 2000 TJ Sport about 5 months ago, it had dangerously bald tires but I didn't gaf and took it mudding within the first month of ownership. Ironically, it had no issues while mudding; the real downside was when I was returning home it was pouring and hydroplaning would get so bad in 2WD that when I drove the 2 1/2 hours back on the highway (@75mph average), I left it in 4HI the whole time(yeah, I know, it's not good for the drivetrain- lesson learned). Anyways, I used my 4HI i few more times that week bc of rain/snow sludge etc. and eventually it had either the chain or some other component in the t-case wear or break on me causing a god awful noise to occur when i put it 4hi/4lo and hit the gas in addition to it not working(2wd has been fine).

So once I did some research and was able to definitively identify the t-case as the culprit, I first looked into rebuilding thinking this was the most cost effective route; this was in fact more expensive to buy kit than just outright replacing(even if I did the rebuild myself), so I crossed that option off and looked into buying a used t-case. Because used tj np231j transfer cases from local junkyards in my area are sparse atm- about 150-250 dollars- i tried to find a more cost effective solution, and found that TJ-era XJs use the same transfer case with a longer input shaft. So great, found one near me for $90 with a 6 month warranty and picked it up. Worst case scenario, I would swap the input shafts and call it a day.

Now this is where I get to the interesting part. In my time researching compatible np231 t-cases from other vehicles, I came across a few forum threads stating that in theory, an XJ np242 transfer case could be mated to a tj[Link a/b]. The upside to having a np242 instead of a np231 is that I have the ability to activate full-time 4WD(which means I will basically have AWD) and still retain my full time 2WD capabilities and part time 4HI/4LO including the same 4LO 2.72 to 1 crawl ratio. After asking people on the wranglerforum[Link c], I was informed that is really was possible(also supported by Novak Conversions as being an "unconfirmed" compatible transmission[Link d]), but I would need to get one off an XJ from the TJ-era (bc of need for speedo gear: not grand-cherokee or a dodge, ONLY cherokee). So my question is, what will i need to make an np242 compatible with my TJ? More importantly, what will I need to get that I won't be able pull out of the np231j currently installed on my TJ?

Also if you are in the tri-state area and have a np242j that fits the above criteria (97-01 cherokee) that you would like to swap for my np231 out of a '99 XJ (not my old broken one but the functioning one from the yard with the 6 month warranty), don't hesitate to post in the thread or dm if you'd prefer.

Thanks for reading. I know it's a long read but I felt it was important to give all the details at once so we could avoid the usual first page of just follow up questions on obviously important details that were not mentioned.

My TJ's Technical Details:
2000 Jeep Wrangler Sport
4.0L I-6
no lift
30X9.5" BFG KO2 AT tires on 15" rims(stock sizing)
stock dana 30s diffs and axles front and rear
NV3550 transmission
np231j transfer case
stock driveline

shoutout to wranglerforum member Digger84. This guy has been a big help in getting answers about what I need to look for when trying the find the right t-case for my specific application. Most of the time he knew what answers I needed before I even asked and has just been an all around good sport about dealing with my dumb questions LOL.

links mentioned:
c :

I also have a YT channel I just started where I will begin posting content on my TJ. I will definitely post a DIY guide for swapping from a np231 to np242, so subscribe if you want to see that:
1 - 1 of 1 Posts