Transfer Cases and Components

How Transmission Transfer Cases Work

A transmission transfer case mounts behind your transmission and sends engine torque to the rear axle, the front axle or both. Its output shafts connect to your driveshafts, yokes and U-joints, which carry torque to the differentials and rear end components at each axle. Most units give you three ranges: 2WD for daily driving, 4-High for slick roads and 4-Low for crawling, towing or steep grades.

4-Low uses a gear reduction to multiply torque, so you get more pulling power at low speed. A part-time system locks the front and rear outputs together, which is why you shouldn't run it on dry pavement. Full-time and AWD units add a center differential or clutch pack that lets the axles turn at different speeds.

Because the transfer case ties the whole driveline together, check related transmission and drivetrain parts when you replace one.

Remanufactured Transfer Cases by Model

Our remanufactured transfer cases come from Zumbrota and cover Jeep, GM, Ford, Ram, Dodge and Cadillac applications. Match the model number on your case tag to the list below, then confirm fitment with your vehicle.

Here are the models and fitments you can shop:

• NP231: 2003-2006 Jeep Wrangler
• NP246: GM 1500 with 4L60E and 2003-2007 GM pickups
• NP261 and NP263: 1999-2007 GM pickups
• NP271: 2003-2012 Ram 2500/3500 and 1999-2005 Ford F250
• NP273: 2003-2005 Ram 2500/3500
• NP133 electric shift: 2002-2003 Dodge Durango
• NP126 electric shift: 2002-2009 GM crossover SUVs
• BW4406: 1999-2008 Ford F150/F250
• BW4418 and BW4419: 2009-2011 and 2009-2014 Ford F150
• BW4444: 2011-2015 Ram 1500
• BW1354: 1998-2000 Ford Explorer and Ranger
• BW1350: 1987-1989 Ford Ranger and Bronco II
• BW1128 manual shift: 2011-2016 Ford F250 and F350
• MP1226 manual shift and MP1626: 2007-2010 GM 2500/3500
• BW4477: 2010-2014 Cadillac CTS

Manual vs. Electric Shift Transfer Cases

The difference is how you select a range: a manual-shift case uses a floor lever, and an electric-shift unit uses a dash switch. Manual-shift units have fewer electrical parts to fail, and you can feel the lever engage each range. You'll find them in Jeeps and heavy-duty trucks, including the NP231 and the BW1128 for 2011-2016 Ford F250 and F350 models.

If you're building up a Wrangler, our Jeep Wrangler upgrade guide covers other changes worth planning around.

Electric-shift units, such as the NP133 and NP126, add convenience but depend on a shift motor, encoder and control module. When one of those fails, the case may refuse to change ranges even though the gears inside are fine. Diagnose the electrical side before you replace the whole unit.

Swapping from one style to the other usually means changing wiring, controls and sometimes the case itself, so it's simpler to replace like with like.

Signs of a Bad Transfer Case and When to Replace It

Grinding, fluid leaks, jumping out of 4WD and getting stuck in 2WD or 4WD are the signs your transfer case needs attention. Watch for these symptoms:

• Grinding or whining that changes with vehicle speed
• Fluid leaks around the seals, output shafts or case halves
• Jumping out of 4WD under load or on deceleration
• Getting stuck in 2WD or 4WD, or shifting slowly between ranges

Start by checking fluid level and condition, since low or burnt fluid causes noise and wear. A vibration under acceleration may be a driveline-angle problem instead, and our driveline angle guide explains how to measure it.

Replace the unit when the case is cracked, the chain is stretched or internal damage spreads across several parts. In those situations, a remanufactured unit is often quicker than a full rebuild. If the damage is limited to seals, bearings or a shift fork, a rebuild may make more sense.

Transfer Case Parts, Adapters and Related Drivetrain Components

If you're repairing or swapping instead of replacing, shop transfer case components for adapters, rebuild parts and replacement parts. It's the place to start when you need a transfer case rebuild kit or a single part to get your case back in service. Have your case tag number ready, since internal parts and adapters are specific to each model.

Brands include Advance Adapters, which lists transfer case adapters for mating a case to a different transmission. You'll also find Yukon Gear and Adams Driveshaft, a source for driveshaft-related parts.

Swaps often change the length or position of your outputs, so plan your driveshaft work before you order. If the swap also changes how your engine and transmission connect, browse transmission adapters too. Add your vehicle first so you only see transfer case parts that fit.