NP242 Full-Time Option Overview
Full-time 4WD option in some XJs (mostly 'Selec-Trac' equipped). 4 modes including full-time AWD with center diff. Heavier and rarer than NP231.
The NP242 was the Selec-Trac transfer case offered as an option on some XJs (and standard on many ZJs, WJs). Same chain-drive architecture as NP231 but with an additional center differential that allows full-time 4WD operation on pavement.
Modes:
- 2WD high (rear only)
- Full-Time 4WD high (center diff open, AWD on pavement)
- Part-Time 4WD high (center diff locked, off-road)
- Neutral
- Part-Time 4WD low (2.72:1, center diff locked)
Why choose 242: drivers who use 4WD on the road (snow, rain, mixed conditions) without worrying about wind-up in turns. The center diff allows different front/rear speeds. For overland or daily driving, it's a genuine convenience over the 231.
Why not: heavier, more complex, fewer aftermarket support options, and the center diff drains some of the available crawl-ratio benefit because it can unlock unexpectedly. SYE kits exist (Advance Adapters, JB Conversions) but are more expensive than 231 SYE.
Identification: NP242 has a stamped tag on the case with '242' and a serial number. Different shifter pattern (4 detents instead of 3). The case casting is also visibly larger.
For rock crawling: stick with 231. For overland/snow daily: 242 is a nice option but rare. Most builds keep the 231 they came with.
Why it works
- full-time AWD mode
- no wind-up on pavement
- good for snow
Trade-offs
- rare in XJs
- heavier
- fewer SYE options
- center diff complexity
Tools required
- flashlight
- tape measure
Sources
Related
- NP231 Overview (1:1 / 2.72:1)
- Atlas II T-Case Swap Overview
- All Jeep Cherokee XJ guides & tools
- Browse the full DIY database
Written and maintained by an AZ wheeler and driveway wrencher. How we source guides. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.