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The NP241 replaced the NP208 in GM full-size trucks and SUVs around 1988 and stayed in the K-series lineup through the end of the GMT400 era. It is a part-time, chain-driven case with a 2.72:1 low range, a cast iron-tough reputation, and a huge population of trucks still running them. The GM version is usually tagged NP241C.
The chain is the part that wears. A stretched NP241 chain gives warning signs for a long time before it fails, and replacing it is one of the better-value repairs you can do on an old 4x4, as long as you buy the right chain for your variant.
Which Chain Does Your NP241 Use?
This is where people get burned. "NP241" covers several variants that are not identical inside:
- NP241C (GM trucks and SUVs): uses the HV-025 chain, OEM number 4167995. The same chain is cataloged for the NP243, the NP208 and the BorgWarner 1370.
- NP241D / NP241DHD (Dodge Ram): heavier-duty internals in the DHD. Do not assume the HV-025 fits; compare the old chain's width and part number.
- NV241OR / Rock-Trac (Jeep Wrangler Rubicon): a different case with its own parts. Compare before ordering.
The tag on the rear half of the case tells you which one you have. If it is gone, our guide to identifying a transfer case by tag and numbers will help.
Symptoms of a Stretched NP241 Chain
- Clunk when shifting into 4WD, and a second clunk on throttle transitions while in 4HI or 4LO.
- Rattle or slap from under the floor that changes with road speed. Most noticeable in 4WD, because the chain carries no real load in 2WD.
- Front driveshaft slop. Engine off, case in 4HI or 4LO, rotate the front driveshaft by hand. If there is a lot of free travel before it takes up, the chain is long.
- Aluminum in the fluid. Once the chain is loose enough to contact the case, you will see silver glitter on the magnet and in the fluid. That is the point where the case itself is at risk.
- Banging in 4LO under load means the chain is skipping teeth. Stop using 4LO until it is fixed.
Also check the front driveshaft U-joints and the slip yoke. On these trucks, a worn joint or dry spline makes a clunk that sounds a lot like chain lash.
NP241 Chain Replacement Cost
| Route | Typical Cost | Notes |
|---|---|---|
| DIY chain only | Chain + RTV + fluid, roughly $110-$150 | Case comes out of the truck |
| DIY chain + bearing and seal kit | Roughly $250-$400 in parts | Recommended on any case that has never been opened |
| Independent shop, chain + reseal | About $600-$1,000 | Labor is usually 4-6 hours |
| Used or reman case swap | $900-$2,000 installed | Only if the housing, sprockets or planetary are damaged |
While the Case Is Apart
- Seals. Input, front output and rear output seals. Cheap and already accessible.
- Bearings. Feel every bearing. Anything notchy gets replaced.
- Sprockets. Hooked or sharpened teeth mean the sprocket goes too.
- Range fork pads. Worn pads cause the case to pop out of 4LO. See range fork pad wear.
- Oil pump and pickup. A starved pump wears the rear output bushing and bearing.
- Inside of the case halves. Look for a polished track or gouges where a loose chain has been rubbing.
Install Tips
- Drain the case, remove both driveshafts and the shift linkage, unplug the 4WD indicator switch and vent, support the case and unbolt it from the adapter.
- On the bench, remove the rear extension or rear retainer, the pump, and the case perimeter bolts, then split the halves at the RTV seam.
- Lift the mainshaft, front output shaft and chain out together. Never try to work the chain off the sprockets in place.
- Install the new chain the same way: loop it over both sprockets and lower both shafts into the case together.
- Clean the sealing surfaces completely, apply a thin RTV bead, and torque the case bolts evenly.
- Refill with the fluid your owner's manual specifies for the case. GM trucks of this era generally call for ATF in the NP241, but confirm for your year.
Related Reading
If you are not sure the chain is the problem, start with NP241 problems and rebuild cost. Planning a full rebuild instead of just a chain? Our NP241 rebuild kit buyer's guide covers bearing and seal kits. Other hard parts are listed under hard parts in our shop.
HV-025 Chain for NP241C
HV-025 (OEM 4167995) drive chain for NP241C, NP243, NP208 and BorgWarner 1370 cases. Check your case tag first: not every NP241 variant uses this chain.
Shop the NP241C Chain → CoreTransmissionParts.com →FAQ
What chain fits a GM NP241C transfer case?
The NP241C uses the HV-025 chain, OEM number 4167995. The same chain is cataloged for the NP243, NP208 and BorgWarner 1370.
Does the HV-025 fit a Dodge NP241DHD or a Jeep Rubicon NV241OR?
Do not assume it does. Those variants have different internals. Compare the old chain's part number and width, or confirm against the case tag, before ordering.
How do I check NP241 chain stretch without opening the case?
Put the case in 4HI or 4LO with the engine off and rotate the front driveshaft by hand. A healthy chain has only a little free play; a long chain lets the shaft turn noticeably before it takes up.
Can a stretched chain damage the NP241 case?
Yes. A loose chain slaps the inside of the aluminum case halves and can wear through them, and it can skip teeth under load in 4LO. Replacing it early keeps it a chain job.
Should I rebuild the whole case while it is apart?
If it has never been opened and has high miles, replacing bearings and seals at the same time is usually worth it, since most of the cost is labor to remove and split the case.