Hi I've been searching the internet for any kind of information on this modification. I'm working on this. I know there are businesses that offer these at outrageous prices. I won't say names. So I know it's possible to have a AWD, 4H, 2H, N, 4L in a NP 242AMG transfer case. What I intend to do is figure out exactly what is required to do this. I'll will be sharing all information I can. A little more information about my project. I have a M1123 that I'm putting a LBZ Duramax in. I will be using the Humvee case rather than the case from the pickup. So far I've encountered several issues. First the output of the Allison is a larger 29 spline than the 4L80E 32 spline output. I have a 29 spline input shaft from a 98 dodge diesel with manual transmission. It fits the Allison. After I verify that these parts fit I'll post part numbers. Now the case pattern is the same pattern on the output of the Allison is correct. However it's clocked wrong. It's not a semtrical pattern so the only way it would bolt up is literally almost straight up and down. I picked up a NP 241C from a Chevy. I believe I will need the front half of this case to get this orientated correctly. I'm very surprised on how little information is being shared on doing the Duramax swap on these. I ended to change that.

 

ICYMI, High Mobility Multipurpose Wheeled Vehicle! Find a different vehicle to go 2wd.

 

Let me get this straight also. This is not for those who want to argue about weather or not that having a 2wd option is good or bad. There are plenty of other threads like that available online. And they don't help anyone. This is not about openions in any way. What I'm looking for is facts. What I'm looking to share is facts. Period. If sharing useful information here isn't wanted I'll find another website where I'm welcome.

 

Doing some more research I believe I need the shift cam and slide collar from a NP242J out of a Cherokee. These parts I will have to order to verify fitment. Here's some pics of what I have found so far.

Np242amg

Np241c

Np242amg

Np241c

Np242amg

Np241c

 

Made a bit more progress on this. In order to use this Transfer case with the Allison. I'm using the front half of the NP241c (Chevy) case. The front bearing in this case is wider then the Humvee case. There are two different 29 spline (Dodge MT) input shafts available. However the dodge uses a larger inner bearing to support the end of the main shaft. So a bushing is required. I found some shafts available online actually come with this bushing. But I chose to make my own. Still waiting on some more parts.

Wide bearing saft on left narrow on right

 

Have you made any progress with this?

 

Yes and no. I've been busy with other things but I need to get back on this. I found that the Chevy transfer case housing will not accept the shift cam from the Humvee or Jeep. The height of the floor is different. So I had to abandon the Chevy housing and went back to the Humvee housing. But the Humvee housing has the wrong clocking for the Allison transmission so I ended up ordering a clocking ring and I had to redrill my own set of holes in it. Now it should bolt up to the Allison in the proper position. I also had to use the narrow bearing input shaft. It used the correct inner bearing and a bushing was not necessary. I ended up breaking a small part on this case so I need to have it repaired that is why this is still on the back burner at this time. I also want to utilize the tail section from the Chevy so that I will have electric speed sensor. The two cases use a different length shift shaft.

 

 

Sounds like quite the project! I would just be using the 6.5 turbo and the stock transmission. My understanding is I just need the shift rail, forks and indexer. All ya gotta do... I don't know if I want to go through the effort though.

 

Despite the effort, will it be worth it? Are the parts you are putting in consumer grade? or like the rest of the H1; industrial grade.