Drivetrain swap. A couple of questions

I am trying to finish a project long going and need some info. The jeep is an 85 that is getting a FI swap. Donor vehicle is a Comanche with multi port injection 2.5. This motor will be going in along with a new tranny and tranfer case.
I have easy access to a TF 999 which from what I was told pretty much the same as my current TF 904. My question about this tranny is what is the difference and which is better? The 904 is a good tranny in my opinion but needs to have the breather relocated.
I am looking to put in a 231 for a tranfer case but worry about will it mate up to the 904 or 999 tranny? Anything need to be changed in order for it to fit? Adapter or changing output shafts? The vacuum lines on this T/C are for a front dissconnect axle. I belive this is a 231J if I remember correctly. Will this cause a problem for me or can I just plug them and be done with it?
Just trying to get some help with this or some suggestions. I have some time to get this done but time is getting short woriking three jobs to go to Moab next year and I want to bring the WOODY!!
Thanks.

Kim

The 999 and 904 are the same dimensions and bolt pattern. The 999 has two ridges on the end. However, the 999 is a much stronger transmission. It has 5 clutches in each gear pack with the 904 having only 3. Go with the 999. I researched this as I want to get rid of my 909 (a 904 with a lock up converter).

With the NP231, make sure the spline count is the same and it will mate right up.

With the vacuum disconnect, get rid of it and get a Posi-Lok cable actuator. You'll appreciate it. The vacuum discos are really bothersome as they break easy. Too many places in the system that will leak and your 4WD won't engage.

pabloconrad said:

The 999 and 904 are the same dimensions and bolt pattern. The 999 has two ridges on the end. However, the 999 is a much stronger transmission. It has 5 clutches in each gear pack with the 904 having only 3. Go with the 999. I researched this as I want to get rid of my 909 (a 904 with a lock up converter).

With the NP231, make sure the spline count is the same and it will mate right up.

With the vacuum disconnect, get rid of it and get a Posi-Lok cable actuator. You'll appreciate it. The vacuum discos are really bothersome as they break easy. Too many places in the system that will leak and your 4WD won't engage.

Click to expand...

Thanks for the info on the 999. I think I will be picking that up soon. When talking spline count are you talking about tranny output to the tranfer case? How many different spline counts came in the 231?

The reason I mentioned the vacuum lines is that this tranfer case is going into a rig with a non disco front end. I would assume that I can just plug them off because the handle for the tranfer case still locks it in 4x4 but the vacuum lines locked the front axle in on the disco axle. This I don't need.
Thanks for the help.

Kim

I just got some more info at that 999. It is out of an 81 cj-7 and has a 23 spline output. Was there a 231 offered in a 23 spline?

Kim

85xjwoody said:

I just got some more info at that 999. It is out of an 81 cj-7 and has a 23 spline output. Was there a 231 offered in a 23 spline?

Kim

Click to expand...

yup, newer (91+?) XJ's had a 23 spline input into the tcase.

Been doing a little searching on tranfer cases and when searching car-part.com they give listings.
But there was not a listing for a 231 offered with an automatic in a four cylinder. Only in a manual.

Kim

The 89 junker we have for parts had the 2.5L/AW4/231 combo. They are out there, but few & far between. JIM.

I thought there were a few packages out there like that. But will a 23 spline output 999 bolt up to a 23 spline 231? Sounds like a wierd question but I don't know if this swap has ever been done.

Kim

From some research I was doing I read that the 999 was offered with the inline six and has a different bolt pattern than the inline four. I hope what I have read is wrong.

Kim