Rough Country 50-7907 vs JB Conversions 16-1200-1942: TJ slip yoke eliminator

Published 10 September 2026

At a glance

	Rough Country 50-7907	JB Conversions 16-1200-1942
Price	$299.95 MAP as of September 2026	$249.00 on jbconversions.com, September 2026 (listed "Out of stock")
TJ fitment	1997-2006 TJ, 2004-2006 Unlimited; NP231 only	TJ, YJ, XJ with the NP231J case
Rear output shaft	1 3/8 in., 32 spline	32 spline, 18% larger spline diameter than stock
Rear yoke	1310 CV	1310 CV, high clearance
Added rear driveline length, TJ	Not published by the manufacturer	6.5 in.
Case removal	Instructions say remove it	Optional, removal recommended
Install time	Not on RC's page; retailers say 3-5, about 4, or 8-10 hours	Not published by the manufacturer
Warranty	RC lifetime replacement on "most suspension products"; retailers list limited lifetime	Lifetime replacement on the output shaft
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 NP231 in a non-Rubicon TJ uses a slip yoke. The rear driveshaft's yoke slides on the transfer case output shaft to take up suspension travel. JB points out the flaws. The stock 27-spline shaft usually breaks at the speedometer gear. The seal leaks once the yoke drags rust and grit across it.

The bigger problem after a lift is angle. JB puts the stock Wrangler rear shaft at 13.5 in. or less, so every inch of lift steepens it. A slip yoke eliminator (SYE) swaps in a shorter housing and a fixed yoke, and the slip moves into a new, longer CV driveshaft.

Where the slip lives, before and after. The SYE lengthens the shaft and moves the slip splines into it. The pinion then has to be rotated up to point at the transfer case. · Original diagram

Both kits do this the same basic way. Each replaces the whole rear output housing and the mainshaft, so the case gets split. Neither cuts the stock tail housing, because neither reuses it.

Rough Country 50-7907 slip yoke eliminator parts laid out: rear housing, mainshaft, yoke, blue speedometer gear, snap rings, plug and nut — The Rough Country 50-7907 kit. RC's product page still files this photo under the old number, 50-7906. · Photo: Rough Country

Fitment, side by side

Vehicle	Rough Country 50-7907	JB Conversions 16-1200-1942
1997-2006 TJ SE, Sport, Sahara, X	Fits	Fits (NP231J)
2004-2006 LJ Unlimited	Listed	Not named; JB lists by case, not model
2003-2006 Rubicon, 2005-2006 Unlimited Rubicon	Listed by RC, but will not fit (NV241OR case)	Will not fit (NV241OR case)
1987-1995 YJ, 1984-2001 XJ	Listed	Listed
Factory rear driveshaft	Will not work	Will not work (1310 CV yoke)

The Rubicon listing is a conflict to know about. Rough Country's fitment list includes the Rubicon, but its own note says "NP231 model transfer cases ONLY." JB files the Rubicon case separately as the NVG241OR, so we treat the Rubicon as a no-fit for both.

Rough Country's shaft is the post-1997 design. Older cases can use it if the needle bearings come out of the drive sprocket. JB says every year of NP231 can take its kit, with speed sensor variations handled in the packaging.

Specs and construction

	Rough Country 50-7907	JB Conversions 16-1200-1942
Output shaft	1 3/8 in., 32 spline. Alloy not published.	32 spline vs stock 27. US made to NVG drawings, factory heat treat retained. JB claims 54% more torque capacity.
Housing	356-T6 heat-treated aluminum alloy	One-piece cast aluminum, pressure-sealed against porosity, with an internal oil drain gallery
Rear seal	Not specified	Dual spring, dual lip
Yoke	1310 CV	1310 CV, redesigned from Spicer 2-4-5341 for extra clearance, 2.00 in. internal spline length
Other yoke options	None listed	1310 non-CV ($255.00), 1350 non-CV ($255.00), 1350 flange ($284.00)
Kit weight	15 lb	Not published by the manufacturer

JB documents its parts, and Rough Country mostly does not. RC's page gives the shaft size, the housing alloy and the yoke series. JB adds its sealing process, the oil gallery, the seal type and the yoke's clearance. JB also says it has sold the same kit since 1994.

Rough Country 50-7907 1310 CV rear output yoke, showing the internal splines — The Rough Country kit's 1310 CV rear yoke. · Photo: Rough Country

What's in the box

Rough Country ships the 50-7907 as one carton. Its instructions list 10 items:

Rear housing assembly, with the rear output seal, bearing and snap ring pre-assembled
Rear output yoke and rear output yoke nut
Mainshaft
Speedometer drive gear and speedometer snap ring
Mode gear snap ring
Housing plug (Wranglers use it; XJs reuse a vacuum actuator)
Rear and front output spline seals

JB publishes no numbered parts list. Its product page names the new output shaft, housing, seal and 1310 CV yoke. Its instructions also call for a new front yoke locknut and rubber "star" washer, which JB says are included, plus a rear star washer and a threaded O-ring plug.

Install compared

Both jobs are a transfer case teardown. You drain the case, pull the front yoke and the old rear housing, and split the case at its 10mm bolts. Then you move the drive sprocket and mode hub onto the new mainshaft and rebuild with RTV.

Step	Rough Country 50-7907	JB Conversions 16-1200-1942
Case out of the Jeep?	Yes, per the instructions	Optional, but recommended
Case half bolts	20-25 ft-lb	Star pattern, center out
Rear housing bolts	15-20 ft-lb	Original 8mm bolts with RTV
Rear yoke nut	140-150	180 lb-ft
Front yoke nut	140-150	90 lb-ft
Shift rod trim	Only if it sticks out 1-1/2 in.; cut to 1 in.	Only if it measures 10.2 in.; cut to 9.380 in. (typical of 1988-1989 YJ)
Speedometer	Re-index the housing to one of 4 positions by gear tooth count	Blue speedometer gear goes between two snap rings
Final check	Measure for the new shaft at ride height	Shift 2HI to 4HI and back while watching the fork rod

Every figure in that table is from each maker's own instructions for its own parts. Use your kit's numbers, not the other one's. The yoke torques in particular are not interchangeable.

Install time is the soft spot for both. Neither maker publishes one. Retailers quote 3-5 hours, about 4 hours, and 8-10 hours for the Rough Country kit. That spread is wide enough that you should plan around the long end.

The instructions differ in quality. Rough Country's is a 6-page scan with no tools list. JB's walks through each step with numbered photos and flags the one real trap, a mode hub ring that can go in backward.

What it changes on the Jeep, and what else you'll need

JB says its kit adds 6.5 in. of rear driveline length on a TJ. Rough Country does not publish a figure. Either way, the kit is only half the job. The bill for the rest usually matches or beats the kit.

A CV rear driveshaft. Both kits need one. 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, uses 1310 joints, and is built to your measured length.
Rough Country's own shafts. RC lists the 5075.1 and 5074.1 for TJs with 4-6 in. of lift, split by rear axle and transmission. Neither fits Unlimited or Rubicon models.
Pinion angle. A CV shaft wants the rear pinion pointed at the transfer case output. Tom Wood's says that is usually done by adjusting the rear control arms, so budget for adjustable uppers if you have fixed arms.
No transfer case drop. Tom Wood's says an SYE and CV shaft remove the need for drop spacers, and Rough Country staff told a buyer the same.

When is it worth doing? Tom Wood's says a transfer case drop may be enough for 1-2 in. of lift. Past 2 in. it says you typically need an SYE and CV shaft. JB sells a shorter kit, 16-1201, for lifts over 4 in.

Our lift follow-on parts guide puts the driveline in the order of everything else a lift disturbs.

Warranty and support

Rough Country states: "Rough Country Suspension Systems offers a Lifetime Replacement Warranty on most suspension products." Its warranty page sorts parts into categories, and driveline parts are not named in any of them. Retailers list this kit as limited lifetime. Coverage is for the original purchaser, and labor is not covered.

JB Conversions writes that its shaft has gone into "hundreds of V8 equipped Wranglers" without a failure, and that "the new output shaft carries a lifetime replacement warranty." We found no written warranty for JB's housing, yoke or seal. JB takes calls at 337-625-2379.

Neither warranty is as clear as it should be. Ask Rough Country whether driveline parts count as lifetime items, and ask JB what covers the rest of its kit.

Owner reports

These are owner reports, not specs. The main TJ forums and Reddit blocked our tools, so this list is shorter than we would like.

A NAXJA member compared a JB kit with an Advance Adapters kit in November 2017. They found JB's seals double-lipped with springs, and weighed the JB housing at 3 lbs 8 oz. Their verdict: "JB Conversions parts show a more refined product and greater attention to detail." (owner report, NAXJA)
A CherokeeForum member recommended JB Conversions in a 2012 SYE debate. (owner report, CherokeeForum)
Rough Country's own review system showed 4.9 stars from 137 reviews in December 2025. ExtremeTerrain showed 5.0 from 7. These are store-hosted ratings, not independent tests.

Who should buy which

Lowest price, and you can wait: JB Conversions. It is $50.95 less than the Rough Country MAP. Its shaft, housing and seal are better documented, and its shaft carries a lifetime replacement promise.
You need it this month: Rough Country. JB's page marks every version out of stock, and it has shown that label for years. Call JB before you plan a weekend around it.
You want one retail warranty on the whole kit: Rough Country, but confirm driveline coverage first. JB's written promise names only the shaft.
A tall lift with a steep shaft: JB's high-clearance yoke is the only design feature here aimed at high angles. Past 4 in., look at JB's shorter 16-1201 instead.
Rubicon: neither. Your NV241OR needs a different part.

FAQ

Do I need a new rear driveshaft with either kit?

Yes. Rough Country says the 50-7907 does not work with factory driveshafts and needs an aftermarket CV driveshaft. JB ships its kit with a 1310 CV end yoke that needs a 1310 series joint, so the stock slip yoke shaft is out either way.

Will either kit fit a TJ Rubicon?

No. Both kits are for the NP231 transfer case only. The 2003-2006 Rubicon uses the NV241OR, which JB sells separate yokes for.

Can I install either kit with the transfer case still in the Jeep?

JB says its kit can go in without removing the case but recommends removing it. Rough Country's instructions tell you to remove the case and take the whole assembly apart. Both jobs split the case in half.

Do these kits fit a 2004-2006 LJ Unlimited?

Rough Country lists the 2004-2006 Wrangler Unlimited. JB lists fitment by the NP231J case rather than by model and names the TJ, YJ and XJ. Rough Country's own CV shafts 5074.1 and 5075.1 do not fit Unlimited models, so an LJ needs a shaft from another maker.