Rough Country NP231 Slip Yoke Eliminator Kit for 87-06 Jeep YJ/TJ/XJ - Fixed Yoke Conversion, Includes Hardware

The Rough Country NP231 Slip Yoke Eliminator Kit (50-7907) converts the NP231 transfer case from a slip-yoke setup to a fixed-yoke configuration to reduce driveline stress and improve off-road durability.

If you run a lifted Jeep YJ, TJ or XJ with larger tires, the factory slip yoke on NP231 transfer cases can become a failure point under increased driveline angle and torque. This kit supplies the components needed to replace the slip yoke with a fixed output and requires an aftermarket CV-style driveshaft (Rough Country’s extended travel driveshaft recommended) to accommodate suspension travel and prevent vibration. It’s engineered for NP231 transfer cases using the modern output shaft introduced in 1997, and earlier NP231s can accept the kit after removing needle bearings from the stock drive sprockets.

How does this kit strengthen the NP231 transfer case on lifted Jeeps?

Replacing the slip yoke with a fixed yoke removes the unsupported sliding connection at the transfer case output. That fixed connection transfers torque more reliably and removes a common failure mode when larger tires and lifts increase driveline angles and loads.

• Eliminates the rear slip yoke to reduce output shaft stress.
• Creates a fixed-yoke output compatible with CV driveshafts.
• Reduces risk of driveline vibration when used with extended travel driveshaft.
• Includes hardware and components needed to convert the transfer case.

Will this kit work with my Jeep and stock driveshaft?

The kit is specific to NP231 transfer cases and will not function with factory two-piece slip-yoke driveshafts. You must use an aftermarket CV-style driveshaft; Rough Country recommends their extended travel driveshaft to properly handle the new fixed-yoke configuration and suspension movement.

• Fits NP231 transfer cases on 1987–2006 YJ, TJ, and XJ vehicles when equipped with the current-style output shaft.
• Not compatible with factory slip-yoke driveshafts—requires a CV aftermarket driveshaft.
• Early NP231 units (pre-1997) need needle bearings removed from stock drive sprockets for compatibility.

What does the kit include and what additional parts will I need?

The Rough Country kit supplies the transfer-case-side components required to change from a slip yoke to a fixed yoke, but it does not include the replacement driveshaft. You will need an aftermarket CV driveshaft sized for your vehicle and travel requirements.

• Includes hardened adapter components, seals, and mounting hardware for the NP231 conversion.
• Requires Rough Country extended travel CV driveshaft or equivalent aftermarket CV driveshaft.
• Installation may require basic transfer case disassembly tools and mechanical skill.

How does this kit affect drivability and maintenance?

After conversion and installation of a proper CV driveshaft, driveline vibration typically decreases and reliability under hard use improves. Routine inspection of the CV joints and seals remains important, but the conversion removes a frequent failure point so long-term maintenance demands are reduced.

• Improves reliability under higher torque and suspension articulation.
• Can reduce vibration when combined with an extended travel driveshaft.
• Maintain CV joint service and check seals periodically after installation.

Who this is for: The Rough Country NP231 Slip Yoke Eliminator Kit is aimed at Jeep owners who have lifted their YJ, TJ, or XJ and equipped larger tires, and who want to eliminate the factory slip yoke’s vulnerability. It’s also appropriate for off-road enthusiasts upgrading to a CV-style driveshaft to handle increased suspension travel and torque. If you have a stock driveshaft and no plans to fit a CV replacement, this kit is not suitable; conversely, if you want a stronger, more durable transfer case output for trail use and larger tires, this kit is a targeted upgrade. Rough Country backs the product with a limited lifetime replacement warranty for added confidence in off-road applications.