The swap is a success. This is something I thought of doing last fall, got little bits of advice from a member who's performed the same swap, and I finally started it this week after procuring the parts and such throughout the summer.

First of all, let me explain the differences between the two transfer cases and why I decided to make the change.

The stock transfer case in my 1998 Ram is an NP231. It's a basic TC that gives you 4H and 4L. My 1998 Durango has an NP242, which has a Full Time and Part Time division of the 4H, utilizing it's own internal differential. The NP231 falls short, in my opinion, because for the most part when I use 4x4 I am going back and forth over dry or slippery surfaces. The 4x4 is locked in and when on dry surfaces I get binding and tire wear when turning or cornering. The NP242, with it's Full Time 4H option, allows slippage in the transfer case which accounts for the dry surfaces and lessens the effects of that binding and such. My 1998 Durango is so much better to drive when things are slippery as a result of that Full Time 4H option.

Second, let me make this clear. This was NOT a simple bolt in and swap, where everything is good to go, project. I encountered a few problems that many would not deem worth the effort. I was committed so I finished what I started. However, knowing the depth and the issues I discovered...I'd say it's not worth the trouble especially for a truck I drive only occasionally.

Finding the parts wasn't too hard. I got a used NP242 from a 1998 Durango, and the accompanying shifter for it which bolts to the transmission case. I got the shifter and boots because the Ram shifter doesn't have the stop gates like the Durango shifter has, to match the extra gears on the transfer case. I didn't use the Durango shifter boots, but since I have a 1998 Durango I kept them as spares.

Next is a front drive shaft. The Ram uses a flange on the CV end of the front drive shaft, and the Durango uses an open joint shell cap that fits into the yoke in the NP242, and attaches with two 5/16-24 bolts. The best fit and affordable front drive shaft is a 1994 Ford Explorer. It's the perfect length, has the CV joint shell on one end, and is really cheap to find in salvage yards. Mine was kind of trashed so I bought new joints. The joints on the CV end are the same between the Explorer and the NP242 so those are stock Explorer parts. However, the front joint where the shaft meets the Ram's front diff yoke is a jumper joint, or adapter joint that has two different sized caps to fit both applications. Napa sold the jumper joint I needed, Precision brand, part #449. It fits the Ram front diff yoke, and the front of the drive shaft from the Explorer. The CV side of the shaft is difficult to rebuild so I recommend having it done by a machine shop or shop that specializes in drive shafts.

I also bought fresh Dextron III fluid for a change in the transfer case. It was low and dark in color so it was time for service. Best done on a flat and level bench so you can drain it under control and fill it on it's back.

As far as the truck, I parked it nose downhill in my driveway. I did this specifically because when the transfer case mounting nuts are removed, the downward angle keeps the studs in the transmission case by gravity so when it's unbolted it won't fall...it just sits there until you pull it back and lower it down. I chocked the rear wheels with chocks and put the transmission in neutral so I could turn the drive shaft for easy removal and installation. I jacked up the front of the truck just enough to get the wheels off the ground so they could be turned. That'll be explained later.

Finally, I put a jack under the transmission pan. All the work is done aft of the transmission so that jack isn't in the way, and it supports the whole drive line while the cross member is removed and the transfer case is swapped.

First thing I did was get the cross member out to get easier access to everything. It literally blocks the flange bolts from the front drive shaft, and half of the transfer case mounting nuts. The eight nut / bolt combinations that hold the cross member in place are easy to get to and remove, however the cross member will not simply fall down. It is in essence bowed, or compressed, and squeezed between the truck frame rails. I used a spreader bar to separate the frame rails a little to loosen it enough to slide the cross member rearward, and down. Maintain it's orientation, because it goes in that certain way. Next, unbolt the rubber mount block from the belly pan, and finally, unbolt the belly pan from the back of the transmission and remove it from the muffler hanger that's attached to it. Set them aside.

The front drive shaft was easy to remove. Flange bolts and strap bolts at the front. It comes out simply with the help of a pry bar.

Next, unbolt the straps on the rear diff yoke, and pull the shaft out of the back of the transmission and set it aside. You'll reuse the rear drive shaft, but not the front shaft. While you're under there, pop the shifter linkage from the shift lever on the transfer case.

Shifter. In the cab, pop the cap off the shifter ****. Under it is a metric 15 nut. The **** threads off. The boot is clipped onto the bezel so it just pops off and slides up off the shifter shaft. Next remove the bezel by removing the three screws that hold it down onto the cabin floor. The shifter pivot assembly is bolted to the cab floor and there is a secondary plate that is held down under that with two more screws. Remove those and pull the shifter pivot assembly and plate. It'll all come right up and out easily.

Back under the truck. Part of the process is removing the vacuum actuation of the front axle engagement and in essence permanently locking the two shafts together like they are in the Durango. On the back of the front axle, on the passenger side, is the vacuum actuator. It has a skid plate, and is held to the axle with four bolts. Once removed, pull it away, and you'll see the vacuum actuated fork that slides the collar sideways to lock to the two splined shafts together. This happens when you put the truck in 4x4. The vacuum connection on the transfer case also tells the actuator to lock the front axle shafts. This operation won't be needed with the NP242, but the collar needs to be slid over and kept there. The easiest way I found was to retain use of the fork.

If you look in the back of the actuator assembly where the fork is, you'll see it is captured on the shaft by two C-clips. The actuator itself moves the whole shaft, which moves the fork, which moves the collar. I simply removed the C-clip on the driver's side, moved the fork down the shaft, and put the clip back in essentially trapping the fork on the driver's side where it would sit if you had engaged the 4x4. This way, with the vacuum actuator in it's resting position, the fork is keeping the collar in locked position which means the two wheels are now connected at the diff. Once that's done, put the actuator assembly back onto the axle housing, making sure the fork is back in place over the collar and that it's fully engaged. It uses a gasket since there is fluid in the front axle, and if you don't have a new gasket you can clean the surfaces and use silicon. Reattach the vent tube but the vacuum can won't need a connection.

You can disconnect the vacuum lines as they won't be needed. They follow hard lines to the transfer case, and those can be removed as well.

The transfer case has several connections of it's own. The vacuum lines all connect to a port on top, there is a vent tube, and all of those simply pull off. The vacuum lines can all be removed. Pull them up from the engine bay side, they connect to a T up on the passenger side of the back of the manifold. Disconnect the line and put a plug over the now open nipple. You won't need the plastic vacuum lines from this point so as long as you cap the nipple the rest of the system is not compromised.

There are six nuts that hold the transfer case to the transmission. They are all fairly easy to get to with the exception of the top nut. For the easy five I used a gear wrench. For the top one, I used a short socket with a 3/8" drive adapter, which is very small, and lets me use a short 7/16" wrench. You can't even see the nut you're working on, so you feel it, slide the socket and adapter on it, and then reach up and 1/4 turn by 1/4 turn, break it loose and back the nut off. It's difficult to break it but once that's done it's just a slow process of threading it off.

Once the nuts are all removed, the transfer case studs are holding the transfer case in place in the back of the transmission just by gravity. It's heavy, but with your body laying under it, reach up and support it, push up to take the weight off, slide it backwards slowly so the studs come out of the back of the transmission, and like a bench press motion, slowly let the transfer case come down onto your chest where you can roll it off onto the ground to one side or the other. Then you can simply slide it on the ground to get it out from under the truck.

With the transfer case out, the shifter can be put up and bolted to the side of the transmission. Since the transmission was essentially the same case between the 1998 Ram and 1998 Durango, I knew the same bosses would exist and the same shifter would bolt to the case. This is where I ran into issues. First, the body of the Ram sits higher off the drive train than the Durango, so the shifter is much shorter in the floor of the Ram. Second, the hole for the shifter is much smaller on the Ram because there are less gears and the shifter doesn't move as far from end to end. Third, the shifter on the Ram is mounted to the floor so the linkage favors the driver's side, where as the Durango shifter sits near perfectly in line with the linkage, so the hole in the floor is too far to the driver's side. Essentially the shifter won't fit the hole in the body when it's bolted to the transmission.

I solved this with a few different methods. First, I trimmed the hole opening as big as I could to fit under the stock shifter bezel which mounts to the floor. I wanted to use the Ram boot so I made sure everything I did retained the Ram bezel and boot. Once trimmed, I got a lot more room for the shifter to operate, but it was still to far to the left. Next, I used 1" spacers to move the shifter assembly 1" away from the face of the transmission mounting flange. This centered the shifter better in the opening, but it still was too far down in the hole and wouldn't reach it's full motion forward or backward. I solved this two fold. First, I cut the shifter shaft off just above the gate, and welded it back on with a 1" gusset moving the shifter shaft forward 1" and up, and rotated it 180 degrees so it angled more inward and back instead of right and forward. Finally, I needed more height in the shifter, so I replaced the 1" spacers with risers that not only spaced the shifter away from the transmission 1", but it raised the whole shifter more another 2". All this work center the shifter in the opening better, raised it considerably, and angled the shifter rod better for the bezel and boot. It now fully actuates through it's entire range of motion.

Transfer case installation was as easy as removal. Get the case under the truck next to where you would lay directly under the back of the transmission. It's heavier than the NP231, but you can maneuver it up onto your chest / stomach, balance it with good opposing grips, and bench press it up and slide the studs into the holes in the back of the transmission. If you go slow and line it up right they go right in and because the truck is angled down hill, gravity holds it safely in place. All you have to do then, is start the six nuts on the studs, and tightening them all down the same way they were removed.

After the NP242 went in, I had to make up for that 1" space I created towards the driver's side. I did this by turning the adjustable nipple block on the linkage to 180 degree from where it was and swapped the nylon grommets the other way so the linkage would slide in from the inside, taking up that slack. I also had to adjust the linkage out a little to accomodate the rise in the shifter but that's a simple matter of loosening the adjustment bolt and sliding the nipple block forward on the shaft a little bit. This left me with a properly adjusted linkage, and a shifter that fit the opening in the floor, with the bezel and boot installed.

Next you can bolt the drive shafts in. The ear goes in the same way it was removed, and the front will bolt right in as long as you have done the joints properly and have the bolts for the transfer case joke shell. Once they are in and bolted, you can reinstall the belly pan on the back of the transmission, then the rubber mount block, and finally, prepare for the cross member. Again, the frame needed to be spread by a bar so I could get it up and slide it into position. Once in position, I started all the nuts and bolts before releasing the spreader bar and then tightening all the nuts and bolts.

I still have not solved the wiring of the sender that lights up the dash indicator that the case is in 4x4, but that's just a matter of testing what pins send a signal, and which pins light in the dash. It's not an integral part, and honestly if you don't need it you can leave it alone.

The transfer case does require a vent tube, and I tied it into the same vent tube from the front axle vacuum actuator assembly with a T. It'll work just fine.

Make sure your shifter shifts after you bolt the bezel back in, and install the boot and ****. Tighten the **** very good before tightening the nut, or it'll rattle when engaged. Also, since the Durango shifter was designed to use two shifter boots for temps and noise, the setup allowed more road noise than the stock configuration. I solved this with a layer of jute inside the bezel, laying flat, with a cut slit for the shifter to move. This wasn't necessary either, but the extra noise bothered me so I solved it.

I did test the system and it all worked perfectly. The whole operation also solved something that I was trying to diagnose. Sometimes, when I would hit the gas and accelerate quickly, I would hear a chirp. I couldn't figure out if it was the front or rear, and it wouldn't do it on slow takeoffs. It seems that there is a vacuum leak in the system, maybe the actuator itself, and it was ever so slightly trying to engage 4x4 when the engine vacuum changed. Once I got rid of the NP231, vacuum system, and vacuum actuator, the chirping has stopped. I still have a vacuum leak to chase, but one issue has been found and dealt with.

If anyone has any questions, feel free to contact me. It required a lot of hard work and problem solving, but it's a successful swap that I will enjoy each winter.

 

Another advantage of this swap is, the NP242 is a slightly heavier duty t-case, and will take more abuse before blowing up.

I had considered doing this on my truck, but, I have the 241 case, and it is even stronger than the 242.... much as I would love to have full time 4wd..... I have a hard time convincing myself to put in a WEAKER part than what I have.

Excellent swap Sooper. And nice write up. Pics would make it perfect, but, I am not going to ask you to do it again and take them.

 

Well, now that winter is here... I find myself wishing my truck had the 242 case in it, JUST for the Full-time 4wd aspect. Woulda come in real handy last few days......

So, it's been a few months, we have gotten some snow, and I am curious how you are liking this particular swap on your truck?

 

You're totally right, the weather was the perfect testing period for the swap and I have taken full advantage. My Durango is my daily driver, but I have made a point to drive the truck around.

Let me start by saying, that I made another change, which has also affected the way the truck drives and handles, both on dry and inclement surfaces.

I swapped my 16" alloy wheels for some 20" chrome wheels from a 2008 Ram. I actually bought them this last summer and stuck them in the back of the garage until I could afford 20" tires. As luck would have it, I found a full set of near new 2007 Ram factory tires that someone had replaced and put in the shed as backups. They never needed them, so they sold them cheap. I have $300 in the rims and $150 in the tires, plus $80 for mount, balance, and stems.



Aside from the look of the truck changing completely for the better, the handling was so much better is was immediately noticeable. Smoother. Crisper. Softer. It revealed a few weaknesses, like the track bar and ball joints, but nothing that wouldn't pass inspection and things I will only change because I am OCD. Yes, I have a new rear bumper to replace the smashed one on the truck...from when a drunk / high driver rear ended me one night when my truck was on the street.

With the new wheels and tires, the truck drives great in the snow. The factory Goodyear tires are not quite as aggressive as what I will put on when I can afford new ones, but even the difference in tread and width compared to the old wheels and tires is enough to make a difference in snow.

As for the transfer case, it was EXACTLY what I was missing. Last winter, I could see the differences between my Durango's full time 4x4 and the Ram's system. The drawbacks are huge if you know the how both feel and it reinforced everything I believed before I set out to perform the swap.

The only detail I haven't solved yet is the dash lights to indicate the system is engaged. Maybe this summer I will have some time to get it set up so that any selection in the new range turns the dash light on. as of right now, no lights at all, and I simply just remember that it's in 4x4 or look down at the shifter.

I guess what I love most is than when it is in the full time selection, I can't tell except that it grips and pulls effortlessly in the snow, and there is no indication it's in 4x4 on dry except when making sharp turns with no acceleration. Having the front diff locked at all times has not affected the dry driving at all. Can't tell.

There really is no other way of saying that it was a great idea, good execution, and near perfect result. Granted, it was not an easy swap, and there are things that might need to be thought out better like the opening for the shifter and a bracket to move the shifter up. I improvised because I didn't want the swap to drag out for weeks...and it worked, but being OCD I have thought of different ways to accomplish the quick fixes I did at the time.

All this being said, my Durango is still better in the snow than my Ram...but, now that I have made these changes to the Ram, I will never hesitate to use it.

 

i am seriously considering doing this... as it seems parts are readily available..... got some question for ya, and some ideas I would like to run up the flagpole.

I assume the 242 has no provision for the the vacuum switch....

Any chance of changing the front yoke, to the flange, so the stock driveshaft can be used? Not sure just how interchangeable parts would be, maybe possible to swap the front output shaft from a 231/241, so it has the correct threads/diameter/spline count? (just out of idle curiosity, do you have that info on the stock shaft in the 242?)

I note that you make modifications to both the shifter, and its mounting. Would it be possible to just fab up a bracket to put the shifter into a convenient location, so that further modification wouldn't be required? (aside from enlarging the hole in the floor.)

I don't have any of the parts in hand as of yet, so, some of this may become obvious once I do. I would like to make the swap keep as much of the standard components as possible, and am just trying to see if that is even possible at this point.

Thanks.

Awesome swap.

Side Note: Do you have any specs on the t-case max input torque/continuous input? I am having trouble finding that info. (suppose I should check the manufacturers site.....)

 

Correct, there are no vac ports on the 242. The front diff on the Durango is always locked, so there was no need for a vac switch to engage the front diff...like on the Ram.

I'm not sure about changing the yoke. I honestly never explored that since I think it would be harder and more complicated than grabbing an Explorer front drive shaft and using it. It's just as strong as the Ram's front shaft...it just fits better. You can look into the yoke swap if you think it's a better route, but I didn't even consider that side of it when I planned it.

Making a shifter to fit would be an adventure or sure. The problems are many. First, the body sitting up off of the TC in the Ram. Second, the travel of the throw is longer because of the two extra gear selections. Third, the small opening from the factory in the floor of the Ram. Fouth, placement of the linkage on thhe 242 compared to the 231. The shifter for the 231 also does not have a gate for selections like the 242 does, and honestly without that gate it'd be too easy to miss a shift. The Durango is suh a unique design, it'd be really hard to try and reverse engineer it to fit and work like the Ram shifter did.

I did not find any torque figures either, but my Durango has the same 360 / auto as my Ram, and me beating the crap out of the 242 in it since 1998 is a true testimate to the strength of the 242. My Durango 360 is not stock.

By the way, and you may want to look into this, but I think there were two versions of the 242 based on a few things I read. The Jeep version seems to be a weaker version that the one in the Durango. The Durango 242 seems to be linked to the name, 242 HD. It might take some digging, but there may be a HD version for Durangos and a standard duty version for the Jeep SUVs.

Keep me posted on what you figure out. I would have been more detailed and clean in my shifter mods, but again, I wanted it all done that day so I rushed through it. That also explains why I didn't stop to take pics.

 

Actually, I think there are at least three different versions. I plan to score one out of a durango, as I know that one will bolt up to my trans.

I would like to be able to use my stock shaft, as I have a 3/4 ton truck.... and my shaft is beefier than the explorer shaft.....

I don't want to build a new shifter.... just wondering if a bracket would solve most of the problems for the 242 shifter. I understand the need for the gates. Just trying to make my life easier.

Is the switch for what mode you are in mounted on the t-case, or the shifter?

 

I have seen these with the vac switch on them, these were also used in the H1 and H2.

So far I have found this.

I quote "the NV242 has a max torque capacity of 1,486 ft. lbs. in the Jeep version and weighs 86 lbs. There is also an NV242 HD with a max torgue capacity of 2028 ft. lbs. and the Hummer version is rated at 2340 ft.lbs.

Thats a far cry from the nv241's 5,555 rating.

 

Found that too, and other numbers as well, but, what they didn't mention was, is that the actual MAX torque? Or is that the max CONTINUOUS torque? I can find values for both numbers for the 231, and 241, but, not for the 242..... Now, according to NVG's naming convention, the second number in the model is it's 'relative strength', with goes from 1, to 7. As it is also a '4'..... one would think it would be at least similar to the 241? Doesn' that make sense?

 

The switch is mounted on the TC. I even tried putting the 231 switch in the 242, but it does not fit.

Also, the Durango has a light for both part time and full time, and I contemplated sourcing a Durango gauge cluster to put in the Ram, but that would mean sutting and splicing into the main wiring harness and I wanted to avoid that.

On top of that, I don't think it matters to me if it says part time or full time...I just like the light telling me it's engaged. I was just going to probe some wires, and splice it all together so no matter what gear I am in, the 4x4 light illuminates and does not when in nuetral or 2x4.

I wish you best in the yoke swap. You might have to snag some parts and compare. Maybe get a junk 231 to take apart, and a 242 to modify. Worst case, the yoke swap won't work and you can put the 242 back together and just have your front shaft modified by a specialized shop.