Frankenbuilt XHD Big Chain – Jeep Transfer Case Upgrade

Why the Jeep should get a transfer case upgrade. 

As Jeepers who wheel our rigs, most of us are VERY hard on certain components, and the transfer case is one of them. The NP241 and NP421OR Rock Track 4:1 found in the Rubicon are both very stout units, however they aren't invincible. With bigger diameter tires, we have more leverage, and unless geared low enough, that means more torque on the chain that drives the front axle. With low tire pressures and lockers we increase traction, which also increases load on the chain. Finally, there is the issue of weight. Most of our rigs are far heaver than you'd guess, in fact, our Jeep Camper weighs in at around 6,500 lbs when loaded - much like a 1 ton truck. All these factors combine to give the transfer case in our Jeeps a tough job. 

Transfer case chains can stretch with heavy use, and they can wear prematurely. The stress on the chain is most often due to a minor difference in wheel speed front to back when traction is good, like on rock or pavement. Another situation that puts a lot of stress on the chain, is when the front end has good traction and you send a lot of torque there. The 3rd situation that is especially hard on this chain, is when you have a spinning wheel suddenly grab traction. This causes a brutal shock load that is unfavorable for most of the drivetrain. While the NP241/NP241OR is very reliable in most rigs, it becomes a little less so with serious 4x4 use in heavy modded rigs. Fortunately, we found a way to improve on this legendary transfer case.

An easy solution exists - The FRANKENBUILT XHD Big Chain upgrade. 

After endless digging through countless catalogs and measuring many parts, we found the solution. Beefy parts from the NP261XHD and NP263XHD found in 2001-2007 GM 2500 & 3500 trucks with 6.6 Duramax or 8.1L V8. This bigger chain and sprocket set, drops right in to the NP241OR Jeep case without any modifications, and can be on your doorstep from Amazon in just a few days. 

Upgraded Jeep transfer case chain comparison:

The chain we dug up has 12 links at the weakest spot instead of 10, so that alone would mean a 20% strength improvement, but that's not all. Also, The XHD chain is a simpler pin type chain, so it should take impact loads better than the rocker style that came in our Jeeps. The individual links on the big chain are the same width as those found on the Jeep chain, but they are 8.13mm tall vs the 7.16mm links from the Jeep. This is another 13.5% strength increase over the stock chain. I'll let the pictures do the talking:

How the XHD chain fits. 

The sprockets are only wider at the teeth, and have the same thickness at the hub, making them a direct swap into our transfer cases. Additionally, the chain fits in the case without any cutting or grinding, making this a simple remove and replace exercise. Simply follow the service manual for disassembly/reassembly steps and torque specs. Here's some pics of the chain installed, with both case halves assembled - plenty of clearance: 

Final thoughts for now... 

The transfer case is installed and working perfectly as it should. We've only been running this chain since April 6th 2025, so there's not much to tell, and frankly, there shouldn't be. This Jeep transfer case upgrade should just reliably and quietly put up with more abuse. And for those of you who made it this far and intend to do the job, I'd recommend pulling the case to do the upgrade. While it can be done in the rig, it is much easier on the bench. As a final tip, get some of these grade 8 transfer case nuts to replace the soft, likely rounded off stock nuts. These things are cheaper than OE replacements, and much more durable - they really saved my bacon.