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Discussion Starter · #1 ·
I've got a ' 74 Ramcharger 4WD with Torqueflight 727 and a warmed over 360 and I'm contemplating swapping out my heavy cast-iron full-time NP203 to a NP242 part-time/full-time aluminum cased unit to cut down on weight and give more wheel drive options. I don't want to give up my full time 4WD or I'd just switch to a NP205 or NP241. Have any of you had any experience successfully pulling off this swap? Will the NP242 handle big-block torque? Will I have to change out my nifty big-ass chrome stock transfer case shifter?
 

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isnt the 242 a drivers side drop tcase? that right there means u need a flip kit for it or a new front axle.

Duane
 

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Yes the 242 is used in Hummer, Durango, XJ and ZJ Jeep applications and is drivers side drop.
 

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Discussion Starter · #4 ·
Rats. What about the NP241?
 

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if u get it from a 88-93 Dodge Ram or RamCharger, then its passenger side drop. u would need a new tranny tail shaft, tcase adapter, and probably driveshafts.

Duane
 

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The 242 isn't commonly used behind large engines or big block torque, so I'd be leery of the swap until I had more info on this t-case. OTOH a 241 should work. You'll need to swap tailshaft mounts to install it. Whats wrong with the 203? They make part time conversion kits for it, and the chain is stronger. Unfortunately strength does cost weight, that cast iron case is very durable.

The 241 does have a lower ratio low range gear than the 203

Ed
 

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u can get a wider chain for the 241 to replace the weak one. some say this make the case as strong or stonger than a 203.

Duane
 

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Discussion Starter · #9 ·
In reply to both Ed and Duane, in my experience, the NP203 is really stout but I'd like the option of 2WD for increased gas mileage because I use this truck as a daily driver for work. I was thinking of the NP242 at first due to the 2WD/FT4WD/PT4WD options this would give me but since it was never offered behind a big block or a hot 360 from the factory, but I think this option is out unless someone offers a some type stout chain upgrade for this unit, not to mention the hassle of installing a flip kit and having new axles made as well as converting to a fixed yoke. I'm a little leery of converting the NP203 to part time 4WD as I've heard that there are some lubrication problems that may arise, such as having to shift into part time 4WD every 200 miles or so to lube the transfer case properly. So, it seems that the NP241 swap with the wide chain upgrade would be my best bet, although I'll really miss my full time 4WD option. Just recently, I pulled my front driveshaft to diagnose a really annoying squeak (which happened to be my front driveshaft CV joint, a little cleaning and lube and all is good!!), and took a spin around the block with my transfer case in 4Lock. We had a bit of snow lately and I was alll ooooverrr the rrroad!!! I didn't realize how much the FT4WD really helped in the snow.
 

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if better gas milage is ur reason for going to a part time case, dont waste the time unless u are REALLY desperate for some milage. at most i have heard of 1mpg, rarely more.

Duane
 

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Orangezilla said:
In reply to both Ed and Duane, in my experience, the NP203 is really stout but I'd like the option of 2WD for increased gas mileage because I use this truck as a daily driver for work. I was thinking of the NP242 at first due to the 2WD/FT4WD/PT4WD options this would give me but since it was never offered behind a big block or a hot 360 from the factory, but I think this option is out unless someone offers a some type stout chain upgrade for this unit, not to mention the hassle of installing a flip kit and having new axles made as well as converting to a fixed yoke. I'm a little leery of converting the NP203 to part time 4WD as I've heard that there are some lubrication problems that may arise, such as having to shift into part time 4WD every 200 miles or so to lube the transfer case properly. So, it seems that the NP241 swap with the wide chain upgrade would be my best bet, although I'll really miss my full time 4WD option. Just recently, I pulled my front driveshaft to diagnose a really annoying squeak (which happened to be my front driveshaft CV joint, a little cleaning and lube and all is good!!), and took a spin around the block with my transfer case in 4Lock. We had a bit of snow lately and I was alll ooooverrr the rrroad!!! I didn't realize how much the FT4WD really helped in the snow.
There really aren't options to have both a part time and full time transfer case in one. You either have to choose one or the other.

As for the 203 conversion being weak. I think this was a myth perpetuated by one of the 4wd rags. I installed a Mile Marker PT conversion in an old 78 Furd I had, and it was fine for over 6 yrs and 70K miles. These were very popular mods done back in the 80s, in those days there were increases in fuel prices and alot more full time 4x4s on the roads. No one I ever knew who used them ever had a problem.

The full time conversion will give you very minor gains in fuel economy, so the best option to gain some real mileage would be to swap in an overdrive type tranny. (And a diesel)

Ed
 

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Discussion Starter · #12 ·
If all I can expect is 1 mpg increase as Duane says, I'll keep the NP203 Ed. I'm not all that concerned about mileage unless I would see a substantial increase. The full time case has been good to me so far, and has put up with some abuse from me as well. Maybe it's better to leave well enough alone. I mean, if I was really concerned about mileage, I probably wouldn't be running a 218/224 duration at .050 lift cam and be contemplating a higher stall torque converter! I'm an old hot rodder at heart (I'm your age!) and have only been into 4WD's about 10 years after moving into my present geographical location. Maybe I was just looking forward to doing some burnouts in a 4500 lb truck! I've done a bit of easy trail cruising out here too, and was looking forward to the lower 2.72 gears, but if I really want to get radical, I'll get an Atlas!
 

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on a side note, u dont want a stall converter if u off road. itll build up a whole lot of heat. u should just stick with a stock converter.

Duane
 

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Discussion Starter · #14 ·
Good thinking Duane, that thought hadn't crossed my mind yet, but the converter I'm looking at will only add about 400 to 600 rpm of stall, just enough to unlock at idle and bring my engine a bit closer to it's torque peak. If I run into any high trans temp problems on the trail, I'll add a larger trans cooler and be sure not to use the built in radiator trans cooler.
 

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I have a part time 203 in my 79. I love the fact that I have 2wd lo and hi, as well as 4 hi and lo.

I didn't notice an increase in gas milage.

If you do the swap to the 241 you won't need a new front driveshaft (borrowed OBXCHARGER's front) but you will need a shortened rear
 

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ok, so after reading through all of this, I got a question.  I'm faced with this choice soon as I have a 440/np435/203 I'm wanting to put into my 85 ramcharger.  So what is the best way to go?  the 203 with the part time kit or the 241 with the wider chain kit, I have both tc's, so basicly whats cheaper, and whats stronger if I want to keep the part time 4x option?
 

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I converted my 203 to PT over 25 years ago (did not do the hubs) using the Mile Marker kit. It will give you tru 2WD in 4HI and 2HI. I did not notice any real gain in mileage but driveability improved and I can "shift on the fly". I have read about the oiling issues but they have not surfaced with my rig. I have never had the 203 out of my truck in the 36 years (and 300k on the odo) I have owned it and other than the kit install, have never been inside it, same chain. I have had the cover off a few to check things out but if it ain't broke, I ain't gonna fix it. The shifter did finally die but thats an external fix. While I am not sporting a big block under the hood, even with a SB and a 435 and 4:11 gears I know I have strained it many times and everything has held up, so far. ;D My service schedule has been  pretty intense since I got the truck and that may have contributed to its long life.
 
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