Transfer Case New Process Model 231
We offer quality transfer case parts and rebuild parts kits that are designed to be top of the line overhaul kits. The New Process 231 series transfer case started to be installed in Jeep, Dodge, and Chevrolet applications in 1987. These transfer cases are part time four wheel drive with shift positions 4HI - 2HI - N - 4L. The NP231 is 1:1 direct drive in high range, and use planetary reduction gears for low range with a ratio of 2.72:1. This unit is chain driven front output, left hand drop (front drive shaft on driver's side) on the Jeep and Dodge, while GM had right hand drop and even a few with drive side drop. The 231 are a light duty transfer case typically used in 4 and 6 cylinder Jeep, Dodge and Chevy applications. These New Process cases have a circular tag on the rear of the case, near the center close to where the rear drive shaft exits. Identification infomation for the NP231 transfer case is on this tag typically includes model number, assembly number, and serial number and ratio data. When ordering a replacement transfer case it’s most important to provide the assembly number. This number is typically eight digits, four number a rivet/screw head and four additional numbers. Jeep, Dodge and Chevy versions all use a 6-bolt circular bolt pattern. This pattern is non-symmetrical and will only bolt up one way. Jeep units and Dodge units are general interchangeable, however Chevrolet units are not. While GM uses the same 6-bolt patter, they have it rotate approximately 90 degrees from that used by Jeep or Dodge. NP231 transfer cases come with either a 21 or 23 spline female input. The 21 spline shaft is frequently found in 4 cylinder applications and the 2.8L V6, While 4.0L 6 cylinder and 8 cylinder applications always used the 23 spline input shaft. The GM/Chevy NP231 is supplied with a 27-spline female input A cross reference table is provide to assist you in identification of your transfer case. Check tag located on rear of unit for model number. An illistrated drawing is provide below to assist you in parts identification, ordering and assembly. Back to transfer case parts availability page.

New Process Model 231			231 Transfer Case Illustration Exploded View to assist you in part identification and assembly.
Part-Time Transfer Case Vacuum Shift			231 Transfer Case Saver $39.29 will not work on 3 bolt trailhousing units
GMC / Chevrolet T-Series 1988-97 / Jeep XJ, YJ and TJ 1986-On / Dodge Dakota 1988- On			Recommended fluid for NP231 -- ATF
PART NUMBER	PER UNIT	DESCRIPTION	TYPE	YEARS	COST
K231000		Rebuilder Kit - Bearings, Gaskets & Seals, Small Parts and Pads	w/BD50-8 Input Bearing	1986-96	$180.84
K231000A		Rebuilder Kit - Bearings, Gaskets & Seals, Small Parts and Pads	w/6010N Input Bearing	1992-On	$170.64
K207900		Overhaul Kit - Gaskets, O'Rings and Seals		1986-On	$34.68
201207C	1	Adapter to Transfer Case Gasket	Chevy / GMC	1986-97	$3.30
201049	1	Adapter Housing Seal (trans side)	Jeep / Dodge - Not in Kits	1986-On	$4.96
201032	1	Input Gear Seal - Double-Lip	Chevy / GMC	1986-97	$7.80
201050	1	Input Gear Seal	Jeep / Dodge	1986-On	$4.60
201040	1	Front Output Shaft Seal 38mm I.D.	Chevy/GMC/Jeep/Dodge	1986-96	$9.00
201040A	1	Front Output Shaft Seal 28mm I.D.	Chevy/GMC	1994-97	$9.00
45551B	1	Rear Output Shaft Seal 27 Spline Outputshaft	Chevy/GMC	1988-83	$7.08
34743A	1	Rear Output Shaft Seal 32 Spline Outputshaft	Chevy/GMC	1992-97	$6.82
12925D	1	Rear Output Shaft Seal 2.563" I.D. 2.372" O.D.	Jeep / Dodge	1986-00	$7.56
45551B	1	Rear Output Shaft Seal 1.500" I.D. 2.372" O.D.	Jeep / Dodge	1986-00	$7.08
201040J	1	Rear Output Shaft Seal 2.584" O.D. (Not in Kits)	Jeep / Dodge	1995-00	$27.92
8008	1	Extension Housing Bushing 1.635" O.D. (Included in Kit)	Chevy / GM / Jeep -	1986-On	$9.42
201449	1	Extension Housing Bushing 2.013" O. D.	Chevy/GMC	1992-97	$11.50
12501A	1	Extension Housing Bushing 1.695' O. D.	Dodge	1988-On	$9.78
201501	1	Input Ball Bearing	BD50-8	1986-96	$47.18
201506	1	Input Ball Bearing	6010N	1992-00	$24.58
K201300	1	Fork Pad Kit	Included in Kit	1986-On	$13.22
201941	1	Range Fork - #16976 or 17833	Aluminum Update	1986-93	$39.90
201942	1	Range hub		1986-93	$101.12
201107	1	Synchro Ring	48 Teeth	1986-97	$72.56
ALT16209		Oil Pump Assembly			$39.94
ALT15832		Switch, Vacuum	4 prong black		$19.20
ALT15664811		Switch, Vacuum	3 prong black		$34.60
207888	1	Drive Chain - 4.3L GM	1.25" Wide - 31 Links	1988-90	$121.81
207888	1	Drive Chain - GM & 5.2L Dodge	1.25" Wide - 31 Links	1991-On	$121.81
231888	1	Drive Chain - Except above	1.00" Wide - 31 Links	1986-On	$119.39
MTC		Heavy duty upgrade Sprocket (Set) and Chain Dirve			$218.79
TRX231		Book on CD Rom, Troubleshooting & Overhaul Guide			$39.96

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transfer case parts

In addition to the transfercase parts and accessories listed here, we also provide an impressive list of automotive after market products for car, pickup truck, SUV and 4wd repair parts and accessories that includes rear end covers, ring and pinion gears, OE clutches and heavy duty performance clutches, diesel gauge kits, exhaust brakes, re manufactured manual and automatic transmissions and both manual and automatic overhaul kits. Other products we offer for the RV recreational vehicle market include REMCO drivelinedisconnects, tow bar and baseplates and auxiliary overdrive units to improve vehicle performance and save fuel. We have a complete 4 wheeling drivetrain product line including complete differential assemblies, limited slip and other solid locking positractions. We offer transmission conversion kits including the NV4500 and NV5600 as well as replacement kits for light duty GM and Jeep transmissions. You may be interested in visiting our Ford and Powerstroke Diesel page, Dodge Ram and other Jeep pages for detailed information.

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