I know the basic differences between the transfer cases that come in our jeeps but I have some particular questions that I couldn't get an answer to by searching the forums.

My ex got my '99 Cherokee when we split and she isn't the least bit mechanically inclined, or does she have any real world experience driving a selectable 4 wheel drive vehicle. She really needs an all wheel drive so that when winter arrives she can just put it into full time 4WD and leave it there for the winter.

The '99 has the NP231, which means she can't do that. Now I have a friend that has a 5.9 Grand that has been thinking about changing out the transfer case so he have have true 2WD. How difficult would it be to swap the transfer case in these two vehicles? The 5.9 come with a NP249, correct? Will they be a direct bolt up? Also wondering if I purchased a NP242 (which I believe has a full time 4WD option) would anything else need to be changed? In full time mode how does the transfer case distribute power safely if the front ratio is 3.54 and the rear is 3.55? Are the ratios the same front and rear in vehicles with the 242 and 249?

I'm trying to do this as cheaply as possible (since I had to give her my Jeep) but I'm also trying to keep in mind safety. She can't be trusted to drive around in Buffalo winters in 2WD with my child in her car.

Any help would be appreciated. Thanks

 

Stay away from the AWD 249 case, they have a vicious coupling (sorry can't spell) and those tend to go out and then you got real problems. The 242 is a fairly stong case and can be a bolt in if the imputs are the same. 91 and up have a 23 spline input and come in 3 different lengths so you will need to do some measuring. Both of those cases have what is basically a differential in them that distributes power in full time mode, the 242s version is just way stronger and more reliable.

 

I was hoping the 249 would work, but I can see some drawbacks. I would think it would last longer than normal behind a 4.0L (It's bolted to alot of V8 grands). Seems the 242 is harder to come by (I have one for myself that I'm not giving up yet). Guess I'll do some hunting in the JY next week.

 

3.54 &3.55 are so close you wouldn't have knoen without opening the cover and checking them! this is done so the frt has a slight pull