well heres the situation hopefully someone can help lead me in the right direction....i have an 89 cherokee,automatic trans with a 21 spline output on the trans and a 242 transfer case..i am in the process of lifting 4.5 inches on a rubicon express kit that i picked up cheap from a local junk yard...with the kit i got a 231 transfer case with an sye already in it, and a driveshaft....this was out of a manual jeep and is 23 splines....now heres where it gets trickey, do i swap in a 21 spline planetary gearset and run that with the driveshaft i have??i have the 21 spline 231 planetary..also what else will i need to do??are the shifter linkages different??also i wont have the switch hooked up for the 4wd light either if i run the 231...unles there is a way to fix that as well...i am not concerend about the fact of part time 4wd and all that this jeep is mainly offroad, the only time i will drive it on the road is in a lot of snow....any input would be great, o yeh also if i run this setup on my auto trans will the drive shaft work??i think it will be a little long, but i am not sure...thanks in advance

 

If you want to use the 231 you can swap the input from the 242 with out ant problem.

Now coming from a manual to a auto the drive shaft might be different.

The front will be a bit shorter but the lift should fix that.

The rear you should be ok with..

 

I am going to guess that the rear driveshaft is going to be too long. I have heard of switching the input shafts on the transfer case but only a 21/231 to a 23/231. Never heard of changing 231/242 input shafts. Not sure that will work.

 

well hopefully not i hope it will fit...i ll know tonight cuz i sm gettin ready to go to the shop now and pull out my transfer case to` verify that it is a 21 spline,we shall see..

 

All t-cases, 207, 231, 241, 242 and 249 can interchange inputs. I found that out when I did my 231 swap. See there are 6 different lengths of input and 2 different spline counts.

 

I'v personally have swapped a 21 spline input gear out of an 87 YJ w/231 and manual shift, installed a 23 spline input from a 94 XJ 231 with automatic.

That means the input doesnt have to come from behind the same type of trans, but you'll need to watch length as mentioned by nick.

Now, i have read where some planetaries are different, this might be an issue. Just make sure you run the new input inside the outter planetary ring gear (by hand checking for bind etc) in your 231 to make sure it's compatible.

 

Thanks Nick. I never knew that the shafts were different lengths and that they fit all the cases like that. Do you know the applications for the various lengths?

 

well i tore the 231 apart and installed a 231 21 spline in it, didnt really look at the length but i guess i got lucky cuz the input on the t case slid right over the output on the trans and bolted up tight.....driveshafts fit well...i need to put fluid in the t case and run it to make sure everything is ok, but with the trans in neutral i can spin the driveshafts and they spin together so i guess thats a good sign, if not i still have the 242 t case so i could use that input if i had to...now all i need is an adjustable trac bar, and rear shocks to complete the 4.5 lift...thanks for the help guys