That's a good question, one of which I am not 100% sure what the answer is. I know that Novak would know for sure, so it might be worth contacting them (they're very responsive). I took that chart / info directly from their website.
That's a good question, one of which I am not 100% sure what the answer is. I know that Novak would know for sure, so it might be worth contacting them (they're very responsive). I took that chart / info directly from their website.
So I haven't heard yet but this is information I got from a seller in Colorado online:
"The transmissions in any TJ only need the short length input to clear the sealing surface in the rear of the transmission. The medium length input will also fit into any of the transmissions. The long length input will fit into The AX15, NV3550, NSG370, and 42RLE. It will not fit inside the 32RE however. So the transmission that you have can utilize any of the 3 input lengths. The late TJ's did however most commonly come from the factory with a long length input. That doesn't mean it's what has to go back in, in order to function as designed. I can however build you one with a long length input if you are more comfortable purchasing that one. I know, it's clear as mud. It's taken me a long time and building hundreds of these in order to figure out what books don't tell you."
That sounds like solid information, and advice I would take.
He's right too... most of this information is things that no book would ever tell you. It's stuff that people had to learn the hard way by taking parts from one and trying to fit them on another. I know the factory service manual certainly won't tell you anything about which parts are interchangeable, and that's about as thorough as it comes!
Yeah he certainly sounds like he knows his stuff. Hopefully when others search in the future it'll be helpful
I agree! Thanks for posting that here, because eventually someone will stumble upon it, and it will be helpful!
Bringing back an old thread, here. 
So, I have a '98 with the AX15, which according to the chart in post #5, should be a 23-spline, short input shaft. I've just started looking into the compatibility of running a t-case from a 42RLE with my AX15. There's a potential purchase riding on my getting accurate information on the compatibility, so if anyone has any info, please do chime in. I'm not at all familiar with transfer cases, so I'm trying to get a crash course education so I can determine if I can move forward with the purchase.
Thanks in advance,
Squatch
So, I have a '98 with the AX15, which according to the chart in post #5, should be a 23-spline, short input shaft. I've just started looking into the compatibility of running a t-case from a 42RLE with my AX15. There's a potential purchase riding on my getting accurate information on the compatibility, so if anyone has any info, please do chime in. I'm not at all familiar with transfer cases, so I'm trying to get a crash course education so I can determine if I can move forward with the purchase.
Thanks in advance,
Squatch
I found this 2012 post from another forum. It's got my head spinning...
"OK, this issue really got me thinking, so I decided to do some further investigating.
The factory parts diagrams list the Mopar part numbers for all of the parts in the transfer case, as well as the combination of engine and transmission they are used with. According to the diagrams, there were three different input gears used in the TJ. They break down as follows:
Part# 4796 956; used '97-02 with the 2.5L and AX-5 transmission, this would be the 21 spline input gear.
Part# 4796 965; used '97-02 with both the 2.5L and 4.0L and all transmissions other than the AX-5, which means the 30rh, 32rh, AX-15, and NV3550.
Part# 4897 953AA; used in all TJs from '03-06, with both the 2.4L and 4.0L and all transmissions: 42rle, NV1500/2550, NV3550, and NSG370
Obviously, some of this conflicts with the chart from Novak. Novak says that the 30rh, 32rh, and AX-15 use a short input gear while the NV3550 uses a long one. But according to Mopar, they all use the same one.
So I tried to figure out a way to confirm either way; I ended up looking through about a million transfer case listings on Ebay to find any that were clear on what year/transmission they came off of, and had a clear picture of the input shaft, and here is what I found:
*Note, if looking through these, disregard what the sellers have to say about compatibility, most of them have no idea what they are talking about. What I am specifically looking at is the year and transmission of the donor vehicle, and the length of the output shaft pictured.
**Also, there are dozens of cases listed on Ebay that came out from behind an AX-5 ('97-02 2.5L manual), the pictures all show a very short input shaft (which should be the 21 spline), I did not bother to link any of these since there is no contention over that one.
1999 4.0 Manual Obviously a long input shaft out from behind an AX-15
1999 4.0 Manual again And again with the long input shaft
1998, unspecified engine/transmission However, according to Novak no pre-2000 should have a long input and this one obviously does
2001 4.0 Auto From behind a 32rh, long input shaft again
2001 4.0 Auto again Another long input from behind a 32rh
2001 4.0 Auto yet again Are we starting to see a pattern yet?
2001 2.5 Auto This time a 30rh, again with the long input shaft though
Now we start to see where a shorter input shaft (other than the 21 spline) actually does start to show up:
2004 or 2005, unclear, unknown transmission But a short input shaft
2005 unknown transmission But again with the short input shaft
2005 4.0 Manual Hard to see the input shaft in the picture, because it's obviously a short one
2006 4.0 Manual And another short input shaft
So, most of these clearly contradict the chart that Novak put together. However, they all match perfectly with the Mopar part #s and application for input gears. It also fits with the transfer case I just got with a short input from behind an '06 manual. Furthermore, I did not see a single listing that showed a case from behind a 30rh, 32rh, or AX-15 that housed a short input gear.
Here is what I think happened. All TJ transmissions except the AX-5 worked fine with the 23-spline long input gear, until 2003. Then, in '03 Jeep started using the 42rle auto transmission. For some reason, the long input gear was not compatible with the 42rle; there probably was not enough room for it in the 42rle housing. So, Jeep shortened the input gear, and for the sake of simplicity started using it also with the manual transmissions, even though they previously worked fine with the longer gear.
Also to clarify, what I am calling the "short" input gear on the '03-06 case is really within an inch of the same length as the "long" input gear. The "21-spline short" gear used with the AX-5 looks like the shortest of them all. Its possible that the shorter '03-06 gear is more what Novak calls the "medium" length. Also, it should be noted then since Jeep shortened the input gear in '03 but didn't switch from the NV3550 to the NSG370 until '05, that at the very least the NV3550 is compatible with both the "long" and "short" 23-spline gears. It is possible that the 30rh, 32rh, and AX-15 might also, but there is nothing in this data to support that. This data does indicate that the 42rle must use the shorter '03-06 input shaft.
So, to bring this all back to the OP's issue, if you are looking for a transfer case that has a 23-spline long input shaft find any case from '97-02, except for ones that were with an AX-5 (2.5L manual). Also, if you have a 2000-2002 with the NV3550, you should also be fine using any '03-06 case, since apparently in '03 and '04 Jeep mated the shorter 23-spline gear with the NV3550 transmission. That should significantly increase your options for donor cases; and, the case you mentioned in the first post may be the only one you actually can't use.
"
"OK, this issue really got me thinking, so I decided to do some further investigating.
The factory parts diagrams list the Mopar part numbers for all of the parts in the transfer case, as well as the combination of engine and transmission they are used with. According to the diagrams, there were three different input gears used in the TJ. They break down as follows:
Part# 4796 956; used '97-02 with the 2.5L and AX-5 transmission, this would be the 21 spline input gear.
Part# 4796 965; used '97-02 with both the 2.5L and 4.0L and all transmissions other than the AX-5, which means the 30rh, 32rh, AX-15, and NV3550.
Part# 4897 953AA; used in all TJs from '03-06, with both the 2.4L and 4.0L and all transmissions: 42rle, NV1500/2550, NV3550, and NSG370
Obviously, some of this conflicts with the chart from Novak. Novak says that the 30rh, 32rh, and AX-15 use a short input gear while the NV3550 uses a long one. But according to Mopar, they all use the same one.
So I tried to figure out a way to confirm either way; I ended up looking through about a million transfer case listings on Ebay to find any that were clear on what year/transmission they came off of, and had a clear picture of the input shaft, and here is what I found:
*Note, if looking through these, disregard what the sellers have to say about compatibility, most of them have no idea what they are talking about. What I am specifically looking at is the year and transmission of the donor vehicle, and the length of the output shaft pictured.
**Also, there are dozens of cases listed on Ebay that came out from behind an AX-5 ('97-02 2.5L manual), the pictures all show a very short input shaft (which should be the 21 spline), I did not bother to link any of these since there is no contention over that one.
1999 4.0 Manual Obviously a long input shaft out from behind an AX-15
1999 4.0 Manual again And again with the long input shaft
1998, unspecified engine/transmission However, according to Novak no pre-2000 should have a long input and this one obviously does
2001 4.0 Auto From behind a 32rh, long input shaft again
2001 4.0 Auto again Another long input from behind a 32rh
2001 4.0 Auto yet again Are we starting to see a pattern yet?
2001 2.5 Auto This time a 30rh, again with the long input shaft though
Now we start to see where a shorter input shaft (other than the 21 spline) actually does start to show up:
2004 or 2005, unclear, unknown transmission But a short input shaft
2005 unknown transmission But again with the short input shaft
2005 4.0 Manual Hard to see the input shaft in the picture, because it's obviously a short one
2006 4.0 Manual And another short input shaft
So, most of these clearly contradict the chart that Novak put together. However, they all match perfectly with the Mopar part #s and application for input gears. It also fits with the transfer case I just got with a short input from behind an '06 manual. Furthermore, I did not see a single listing that showed a case from behind a 30rh, 32rh, or AX-15 that housed a short input gear.
Here is what I think happened. All TJ transmissions except the AX-5 worked fine with the 23-spline long input gear, until 2003. Then, in '03 Jeep started using the 42rle auto transmission. For some reason, the long input gear was not compatible with the 42rle; there probably was not enough room for it in the 42rle housing. So, Jeep shortened the input gear, and for the sake of simplicity started using it also with the manual transmissions, even though they previously worked fine with the longer gear.
Also to clarify, what I am calling the "short" input gear on the '03-06 case is really within an inch of the same length as the "long" input gear. The "21-spline short" gear used with the AX-5 looks like the shortest of them all. Its possible that the shorter '03-06 gear is more what Novak calls the "medium" length. Also, it should be noted then since Jeep shortened the input gear in '03 but didn't switch from the NV3550 to the NSG370 until '05, that at the very least the NV3550 is compatible with both the "long" and "short" 23-spline gears. It is possible that the 30rh, 32rh, and AX-15 might also, but there is nothing in this data to support that. This data does indicate that the 42rle must use the shorter '03-06 input shaft.
So, to bring this all back to the OP's issue, if you are looking for a transfer case that has a 23-spline long input shaft find any case from '97-02, except for ones that were with an AX-5 (2.5L manual). Also, if you have a 2000-2002 with the NV3550, you should also be fine using any '03-06 case, since apparently in '03 and '04 Jeep mated the shorter 23-spline gear with the NV3550 transmission. That should significantly increase your options for donor cases; and, the case you mentioned in the first post may be the only one you actually can't use.
This site contains affiliate links for which Jeep Wrangler TJ Forum may be compensated.
So, a 03 with 42rle can use a short shaft 23 spline?I found this 2012 post from another forum. It's got my head spinning...
"OK, this issue really got me thinking, so I decided to do some further investigating.
The factory parts diagrams list the Mopar part numbers for all of the parts in the transfer case, as well as the combination of engine and transmission they are used with. According to the diagrams, there were three different input gears used in the TJ. They break down as follows:
Part# 4796 956; used '97-02 with the 2.5L and AX-5 transmission, this would be the 21 spline input gear.
Part# 4796 965; used '97-02 with both the 2.5L and 4.0L and all transmissions other than the AX-5, which means the 30rh, 32rh, AX-15, and NV3550.
Part# 4897 953AA; used in all TJs from '03-06, with both the 2.4L and 4.0L and all transmissions: 42rle, NV1500/2550, NV3550, and NSG370
Obviously, some of this conflicts with the chart from Novak. Novak says that the 30rh, 32rh, and AX-15 use a short input gear while the NV3550 uses a long one. But according to Mopar, they all use the same one.
So I tried to figure out a way to confirm either way; I ended up looking through about a million transfer case listings on Ebay to find any that were clear on what year/transmission they came off of, and had a clear picture of the input shaft, and here is what I found:
*Note, if looking through these, disregard what the sellers have to say about compatibility, most of them have no idea what they are talking about. What I am specifically looking at is the year and transmission of the donor vehicle, and the length of the output shaft pictured.
**Also, there are dozens of cases listed on Ebay that came out from behind an AX-5 ('97-02 2.5L manual), the pictures all show a very short input shaft (which should be the 21 spline), I did not bother to link any of these since there is no contention over that one.
1999 4.0 Manual Obviously a long input shaft out from behind an AX-15
1999 4.0 Manual again And again with the long input shaft
1998, unspecified engine/transmission However, according to Novak no pre-2000 should have a long input and this one obviously does
2001 4.0 Auto From behind a 32rh, long input shaft again
2001 4.0 Auto again Another long input from behind a 32rh
2001 4.0 Auto yet again Are we starting to see a pattern yet?
2001 2.5 Auto This time a 30rh, again with the long input shaft though
Now we start to see where a shorter input shaft (other than the 21 spline) actually does start to show up:
2004 or 2005, unclear, unknown transmission But a short input shaft
2005 unknown transmission But again with the short input shaft
2005 4.0 Manual Hard to see the input shaft in the picture, because it's obviously a short one
2006 4.0 Manual And another short input shaft
So, most of these clearly contradict the chart that Novak put together. However, they all match perfectly with the Mopar part #s and application for input gears. It also fits with the transfer case I just got with a short input from behind an '06 manual. Furthermore, I did not see a single listing that showed a case from behind a 30rh, 32rh, or AX-15 that housed a short input gear.
Here is what I think happened. All TJ transmissions except the AX-5 worked fine with the 23-spline long input gear, until 2003. Then, in '03 Jeep started using the 42rle auto transmission. For some reason, the long input gear was not compatible with the 42rle; there probably was not enough room for it in the 42rle housing. So, Jeep shortened the input gear, and for the sake of simplicity started using it also with the manual transmissions, even though they previously worked fine with the longer gear.
Also to clarify, what I am calling the "short" input gear on the '03-06 case is really within an inch of the same length as the "long" input gear. The "21-spline short" gear used with the AX-5 looks like the shortest of them all. Its possible that the shorter '03-06 gear is more what Novak calls the "medium" length. Also, it should be noted then since Jeep shortened the input gear in '03 but didn't switch from the NV3550 to the NSG370 until '05, that at the very least the NV3550 is compatible with both the "long" and "short" 23-spline gears. It is possible that the 30rh, 32rh, and AX-15 might also, but there is nothing in this data to support that. This data does indicate that the 42rle must use the shorter '03-06 input shaft.
So, to bring this all back to the OP's issue, if you are looking for a transfer case that has a 23-spline long input shaft find any case from '97-02, except for ones that were with an AX-5 (2.5L manual). Also, if you have a 2000-2002 with the NV3550, you should also be fine using any '03-06 case, since apparently in '03 and '04 Jeep mated the shorter 23-spline gear with the NV3550 transmission. That should significantly increase your options for donor cases; and, the case you mentioned in the first post may be the only one you actually can't use. View attachment 268552"
This site contains affiliate links for which Jeep Wrangler TJ Forum may be compensated.
A nice drive south on tropical trail might solve that, no?
See the ruins of the dragon?
Srsly though, I spent 3 hrs searching online last night and it's clear as mud to me what t-case an 03 42RLE can use. Other than maybe 23 spline.
Ya got me, Chief. I haven't found any definitive answers to my own questions on the subject, and at this moment, it's no longer a priority (Life happened).
I think the post that Squatch reposted is correct. the 42RLE requires, and may be the only one to require, a short 23 spline input shaft. And since all those made after 03 were short, if you grab one out of an 03-06 TJ you should be good to go.
I can testify that a long input from a 97-02 will mount to an '06 NSG370 (6 speed).
So my options are pretty limited then, unless I want to swap input shafts, I need an 03-06 t-case.
I'm looking for a case to go behind my AX15. Sounds like I could use any length input shaft as long as it's 23 spline?
Is anybody aware of any NP231 differences between different models? For example, an NP231 from a 4.0 ZJ? I don't think there is much electrical or shifter wise to get different, right?
Is anybody aware of any NP231 differences between different models? For example, an NP231 from a 4.0 ZJ? I don't think there is much electrical or shifter wise to get different, right?
depending on the year. Pre TJ, the rear output housing had a long snout on it, and I don't know what implications that carries for compatibility with the TJ's slip yoke, but if you intend to SYE it then it doesn't really matter.
Older ones also had a longer rod in the range selector fork. This still matters if you do an SYE, but only in the sense that you have to cut it down to work with the output housing from your SYE kit. The kits usually include instructions for this.
My NP231 came out of a 2000 XJ, that had been mated to an AW4. I swapped my long input gear into it, installed it with the AX15 in my '99, and then swapped it over to the NSG370 in my 06 LJ. I mix and matched some parts, too, based on what looked healthier. I think I kept my planetary set and input gear, but used the shifting parts and the front output shaft from the XJ, with a new chain.
HAH. So, I just got off the phone with Novak and the tech was looking at photos of the 42RLE. He sees the output shaft on the trans as flush with the housing, which means he thinks the NP231 for the 42RLE was a long input shaft.