Rough Country 50-7907 vs TeraFlex 4444400: TJ slip yoke eliminator
Published 10 September 2026
At a glance
| Rough Country 50-7907 | TeraFlex 4444400 | |
|---|---|---|
| Price | $299.95 MAP as of September 2026 | $399.99 on teraflex.com, September 2026 |
| TJ fitment | 1997-2006 TJ, 2004-2006 Unlimited; NP231 only | TJ and LJ; NP231-J only |
| Added driveshaft length | Not published by the manufacturer | Up to 7 in. over stock |
| Speedometer | Reuses the stock gear-driven housing | Tone ring and electronic sensor; converter box required |
| Case removal | Instructions say remove it | In the Jeep or on the bench |
| Install time | Not published by the manufacturer | 5 hours |
| Warranty | Lifetime replacement on "most suspension products"; retailers list limited lifetime | 1 year |
| Also needed | CV rear driveshaft, and rear control arms that adjust pinion angle | |
What each kit is, and what it fixes on a TJ
The non-Rubicon TJ's NP231 case uses a slip yoke, and the rear driveshaft is short. Lift the Jeep and that short shaft runs steep, which is where the vibration starts.
A slip yoke eliminator (SYE) swaps the rear housing and output shaft for a shorter housing with a fixed yoke. The slip moves into a longer CV driveshaft. The shorter the housing, the longer and flatter the shaft can be.
That is the whole case for the TeraFlex kit. TeraFlex says its Extreme Short Shaft housing is more than 3 in. shorter than a standard SYE kit, and 1.5 in. shorter than an ATLAS II case. It claims up to 7 in. of added driveshaft length. Rough Country does not publish a length figure for its kit.
TeraFlex also sells a standard kit, the 4444401 Short Shaft Kit, for $299.99. It adds 4 in. and keeps the gear-driven speedometer. If you want TeraFlex at Rough Country's price, that is the one to look at.
Fitment, side by side
| Vehicle | Rough Country 50-7907 | TeraFlex 4444400 |
|---|---|---|
| 1997-2006 TJ SE, Sport, Sahara, X | Fits | Fits |
| 2004-2006 LJ Unlimited | Listed | Listed |
| 2003-2006 Rubicon, 2005-2006 Unlimited Rubicon | Listed by RC, but will not fit (NV241OR case) | Will not fit (NP231-J only) |
| 1997 TJ | Fits | Fits with speed sensor pigtail #4990108 |
| Case with a mechanical speedometer cable | Reuses the stock setup | Needs updating to an electronic speedometer |
| Factory rear driveshaft | Will not work | Will not work |
A 1997 TJ needs one extra part with the TeraFlex kit. TeraFlex says 1997 and older Jeeps need pigtail #4990108 to adapt the speed sensor connector to the 1998-and-newer plug.
Some retailers list both kits for Rubicon trims. Both makers limit their kits to the NP231, and the Rubicon does not use one.
Specs and construction
| Rough Country 50-7907 | TeraFlex 4444400 | |
|---|---|---|
| Output shaft | 1 3/8 in., 32 spline | TeraFlex shaft 600069; spline count not published |
| Housing | 356-T6 heat-treated aluminum alloy | Material not published |
| Rear bearing | Pre-assembled in the housing | 6209 output bearing |
| Rear yoke | 1310 CV | TeraFlex yoke 600071, with four 5/16-24 12-point bolts |
| Speed signal | Stock speedometer drive gear | Tone ring and electronic speed sensor 4990254 |
| Kit weight | 15 lb | Not published by the manufacturer |
Rough Country publishes more about its shaft and housing. TeraFlex publishes more about replacement parts. Its catalog lists the rear yoke at $77.99, the speed sensor with harness at $73.99, and the output seal at $11.99.
What's in the box
Rough Country's instructions list 10 items in one carton:
- Rear housing assembly with seal, bearing and snap ring pre-assembled
- Rear output yoke and yoke nut
- Mainshaft
- Speedometer drive gear and speedometer snap ring
- Mode gear snap ring
- Housing plug
- Rear and front output spline seals
TeraFlex's parts list runs to 20 lines. The main pieces are the shaft, the 6209 output bearing, the output seal, the yoke with flanged nut, and the four yoke bolts with lock washers. The rest are for the speed signal: the tone ring and its dowel pin, the speed sensor and connector, the terminals and the split tubing. There is also a 47 mm synchro hub snap ring.
Install compared
Both jobs split the transfer case. You drain it, pull the front yoke and the rear housing, separate the halves, and move the drive sprocket and hub onto the new mainshaft.
| Step | Rough Country 50-7907 | TeraFlex 4444400 |
|---|---|---|
| Case out of the Jeep? | Yes, per the instructions | Optional |
| Stated time | None | 5 hours |
| Tools listed | None | Basic tool set, snap ring pliers, mallet, RTV, red and blue threadlocker |
| Case half bolts | 20-25 ft-lb | 20-25 ft-lb, blue threadlocker |
| Rear housing bolts | 15-20 ft-lb | 15-20 ft-lb |
| Rear yoke nut | 140-150 | 90-130 ft-lb, red threadlocker |
| Shift rod | Trim to 1 in. if it sticks out 1-1/2 in. | Cut to 9.38 in. if it measures 10.2 in. |
| Speedometer | Re-index stock housing to 1 of 4 positions | Fit tone ring and sensor, bolt at 8-12 ft-lb |
| Fluid | ATF to the proper level | 2.2 pints (1.0 L) ATF+4 |
| Official video | None found | 15:25, on a 1998 TJ |
Watch one TeraFlex detail. The four bolts that hold the driveshaft to the yoke must go into the yoke before it goes on the shaft. TeraFlex says "they will not fit" otherwise.
TeraFlex's torque figures disagree with each other. Its step text says 190-230 ft-lb for the front output yoke nut. Its own torque table gives 90-130 ft-lb for the front yoke nut, and puts 190-230 against the rear companion flange nut. Call TeraFlex at 801-713-3314 before you torque it.
TeraFlex's in-vehicle option and stated time make its job easier to plan. Rough Country publishes no time, and retailers quote anywhere from 3-5 hours to 8-10 hours.
What it changes on the Jeep, and what else you'll need
- A CV rear driveshaft. TeraFlex's catalog lists no TJ CV shaft. Tom Wood's sells a TJ double cardan shaft for $399.00 on its own site as of September 2026. It fits the TJ and TJ Unlimited but not the Rubicon.
- Rough Country's shafts. RC lists the 5075.1 and 5074.1 for TJs with 4-6 in. of lift. Neither fits Unlimited or Rubicon models.
- A speedometer converter box, for TeraFlex only. TeraFlex says the kit requires one but does not list a part number or price. One retailer says you need it only when tire size or axle ratio falls outside the calibration range.
- Pinion angle. A CV shaft wants the rear pinion pointed at the transfer case. Tom Wood's says coil-sprung Jeeps get there with adjustable rear control arms.
How much lift calls for all this? TeraFlex's catalog says lifts of 4 in. and up require a CV shaft and SYE, and it highly recommends them at 3 in. Tom Wood's says a transfer case drop can cover 1-2 in. Our lift follow-on parts guide puts it in order.
Warranty and support
Rough Country: "Rough Country Suspension Systems offers a Lifetime Replacement Warranty on most suspension products." Its category list does not name driveline parts. Retailers list this kit as limited lifetime.
TeraFlex: its warranty page puts "Transfer Case; short shaft kits" under its "1 Year Warranty." Coverage is "limited to the original purchaser and the original vehicle." Improper installation and racing void it. Some retailers still print "limited lifetime," which is out of date.
Rough Country wins this one on paper. Confirm driveline coverage with Rough Country before you count on it.
Owner reports
These are owner reports, not specs. The main TJ forums and Reddit could not be read for this article.
- A 3-star Quadratec review of the TeraFlex kit praised the clear instructions and the pre-installed bearing. The owner worried that a broken yoke bolt means pulling the yoke, and that the small tone ring dowel pin could seize. They also noted the bearing shipped exposed in cardboard. (owner review, Quadratec)
- ExtremeTerrain showed the TeraFlex kit at 4.7 stars from 9 reviews. (ExtremeTerrain)
- Rough Country's own review system showed 4.9 stars from 137 reviews in December 2025. These are store-hosted ratings, not independent tests.
Who should buy which
- Big lift, short TJ, vibration you cannot tune out: TeraFlex 4444400. Up to 7 in. of extra shaft length is the one number here that directly lowers the angle.
- A moderate lift on a budget: Rough Country. It costs $100.04 less, needs no converter box, and keeps the stock speedometer drive.
- You want the longest warranty: Rough Country, once it confirms driveline coverage. TeraFlex is 1 year.
- You want to leave the case in the Jeep: TeraFlex. Its instructions allow it. Rough Country's do not.
- The TeraFlex name at Rough Country's price: look at the TeraFlex 4444401 at $299.99.
- Rubicon: neither.
FAQ
Does the TeraFlex 4444400 need a speedometer converter box?
TeraFlex says it does. The kit reads speed from a tone ring and electronic sensor and requires a converter box to calibrate the speedometer. The Rough Country kit reuses your original speedometer gear and housing.
Do I need a CV driveshaft with either kit?
Yes. TeraFlex says the kit must be used with a CV style (double cardan) driveshaft. Rough Country says its kit does not work with factory driveshafts.
Can I install the TeraFlex kit without removing the transfer case?
TeraFlex says the job can be done with the transfer case in the Jeep or on the workbench. Rough Country's instructions tell you to remove the case.
Will either kit fit a TJ Rubicon?
No. TeraFlex says its kit fits NP231-J transfer cases only, and Rough Country says NP231 only. The Rubicon uses the NV241OR.
Sources
- Rough Country 50-7907 installation instructions (PDF)
- Rough Country 50-7907 product page (archived 8 December 2025)
- Rough Country warranty page (archived)
- TeraFlex 4444400 product page
- TeraFlex 999008 installation instructions (PDF)
- TeraFlex 4444401 product page
- TeraFlex warranty
- TeraFlex 2024 product catalog (PDF)
- TeraFlex 4444400 install video
- Tom Wood's TJ double cardan rear driveshaft