I came up with a wise idea the other night. Now while the entire front suspension is out and the entire oil pan is easy access I'm going to install a new rear seal and oil pan gasket.

 

Thats a good idea!

 

I got the old NP242 transfer case pulled out last night. I had forgotten what a joy it is to remove a transfer case from one of these little Jeeps....NOT!!!! Anyway, my old trusty NP231 with slip yoke eliminator will be going in tonight after work.

 

Looking good Buck. Just got done reading through your build, finally. Lol.
And Welcome back stateside brother.

 

soo much easier when they are lifted! lol

 

Got a few finishing touches on the floor this morning. Then its over to the shop to put the NP231 put in and hopefully the new rear seal and oil pan gasket. I've been battling numbness in my left hand and arm for the last few weeks. Going to the back cracker on Tuesday to get it fixed.

 

Today I went over to my shop with every intention of putting the NP231 TC in and getting the rear seal and oil pan gasket changed. However, overnight I decided to do the FST Simple NP231 shift linkage. So I started tonight by removing the old stock transfer case linkage. Once the linkage was out and sitting on the work bench I decided to take a good look at the NP242 and NP231 side by side. They both appear to be pretty close to the same size and weight. I'd read somewhere that the older XJ AW4s had a 21 spline output shaft and newer ones had a 23 spline output shaft but I wasn't aware of when they made the change. I should have known they made the change between the 90 and 91 model years when they changed from the Renix XJ to the HO XJ. So my NP231 being out of a 91 and my new Jeep being an 87 I have the spline mismatch between the old tranny and newer TC. Luckily I happen to have a spare 90s AW4 just kicking around my shop so it looks like that will be going into the new Jeep along with the transfer case. I was hoping to get away with just swapping out the output shaft but, I have read that is major surgery and I already have the other tranny anyway. So I moved on to start removing the oil pan when I made another alarming discovery. 2 of the 6 bell housing bolts were completely missing and another was a bolt that was way to long and the PO made it work by stacking nuts and washers on it. That is what the last picture is. the bolt I removed from my bellhousing and the correct bolt for that spot that I replaced it with. With all the things that I have found jacked on this Jeep since I started taking it apart I am a firm believer that it will run and ride like a Cadillac once I have gone all the way through the drive train and suspension like I plan to and replacing all of it with parts from my other Jeep. The only original drive train component it will have left in it will be the motor and even it will have an HO top end on it. It will have an HO AW4, HO NP231, My built axles and a completely different suspension lift to lift it to 8.5 inches over stock so as to clear 35 inch tires.

 

If you dont want to replace the tranny buck you can replace the input on your 231 very easily. All your need is one from a 87-90 and swap it with your ho one. The sye kit is all the same for 21 or 23 spline. Just a option for you

 

Nathan, do you know if I can swap the 21 spline TC input shaft from an NP242 into an NP231?

 

I would say no.but I just picked up a renix era tc for 60 bucks at pick and pull. U could out there and tear one down for the coupler lol. I haven't done alot of research on the tranny swap but I definitely would do some and make sure all the electronics are the same and that the newer torque converter will bolt up the the renix flex plate. Im pretty sure it all will. If you do pull the trans make sure to inspect the flexplate they are prone to cracking.

 

Yeah I dont have any reason to believe th tranny is,good. It was given to a crack head old roomate of my sons as a spare with a POS Jeep. He left it in their garage when he left. It was a freebee so I snagged it.

 

I think I will pull the pan off the donor 90s AW4 and check the inards out. I already know the torque converter is good. Going with that tranny is the only free course of action I have. Unless I can find someone who has an 80s NP231 at a price I cant refuse.

 

I dont no about over there but here there easy pickings at all of the pick and pulls over here. Any 87 to 90 will work.

 

I think I am going to give swapping the 21 spline input shaft from the NP242 into the NP231, a shot.

 

I searched around buck and found a few sources that says the shafts are interchangeable between 242 and 231. So you should be good to go!

They changed a bit after 95 but since your dealing with both cases being pre 95 I am highly optimistic!