Transfer Case Seal Kit, 263XHD, Duramax | 2001-2007

The Merchant Automotive Seal Kit for the NP263XHD transfer case includes the seals used throughout the transfer case to complete the proper reassembly after a transfer case rebuild or major overhaul. It fits the electronic shift NP263XHD in 2001-2007 Chevy Silverado and GMC Sierra 2500HD and 3500HD trucks with the 6.6L Duramax diesel (LB7, LLY and LBZ), and the NP263XHD used with the 8.1L gas engine.

Features

• The seals for a complete NP263XHD reassembly in one kit
• Includes the front input, front output and rear output seals
• Includes the transfer case to transmission adapter gasket
• Includes the speed sensor, selector shaft sensor and pickup tube O-rings
• Every part in the kit is also sold separately

What's Included

• (1) A23 speed sensor O-ring (10238)
• (1) A13 rear output seal, XHD (22049)
• (1) Transfer case to transmission adapter gasket (331304A)
• (1) Snap ring hole grommet (88958815)
• (1) A7 front output seal (411081A)
• (1) A9 front input seal (411070A)
• (1) Selector shaft sensor and detent plug O-ring (401330)
• (1) B30 pickup tube O-ring, 49 spline pump (12478088)

Before You Order

• 263XHD only. This kit is for the electronic shift NP263XHD (push button or knob on the dash). For the manual shift NP261XHD, see the 261XHD Seal Kit.
• Need bearings too? See the Transfer Case Bearing and Seal Kit, 263XHD.
• RTV not included. You will need RTV silicone to seal the transfer case halves on reassembly.
• Fixing pump rub? See the Merchant Automotive Transfer Case Pump Upgrade and Repair Kit, XHD or the Transfer Case Pump Upgrade Kit with Fluid.

Installation Tips

• Use a seal driver to install the input and output seals squarely without damage. See the Merchant Automotive Transfer Case Seal Driver Kit.
• Seal the transfer case halves with RTV silicone on reassembly.
• Make sure the rear output bearing snap ring is fully seated in the rear housing and in the locating groove of the bearing.
• Torque the transfer case mounting nuts at the transmission output adapter to 37 ft-lbs and the assembly bolts to 27 ft-lbs.

What is a Transfer Case "Pump Rub" Failure?

GM transfer cases used from 1998 through early 2007 have a gear pump inside the case that is driven off the mainshaft. The pump forces oil to the planetary and the drive sprocket sleeve. Because the pump is driven by the shaft, the pump housing must "float" in the rear housing. Tabs around the pump housing fit into spots in the rear housing to locate it and keep it from spinning with the mainshaft. Over time, the pump tabs can start to wear on the rear housing. GM installed a spring steel clip in the housing intended to prevent wear, but the clip can break and be rendered useless.

Since the aluminum pump housing is harder than the magnesium rear housing, it can wear a hole in the rear housing and cause a very small leak. The leak is often high enough on the case that it does not drip when the truck is parked, but it leaks while the truck is moving. Because the transfer case does not have a low fluid indicator, pump rub is often not found until the case has been damaged from running out of fluid. Avoid costly repairs by installing a Merchant Automotive Transfer Case Pump Upgrade kit before it happens to your truck. The pump upgrade kits come with a limited lifetime warranty against pump rub. If you already have a hole in your case, we recommend installing a new rear housing for a complete repair.

Related Parts

• Transfer Case Housing Bolt Kit
• Transfer Case to Transmission Mounting Nut Kit
• Transfer Case Snap Ring Kit, 263XHD
• Merchant Automotive Transfer Case Seal Driver Kit
• Sil-Bond RTV 4500 Silicone Sealant, 2.8 oz
• Merchant Automotive Performance Transfer Case Fluid, 2 Qt
• Transfer Case Pump Upgrade Kit with Magnetic Drain Plugs and Fluid

Frequently Asked Questions

Is the transfer case behind the Allison 1000 or ZF6 in my 2001 through early 2007 truck an NP261XHD or NP263XHD?
The easiest way to tell is the shift selector. Trucks with a floor mounted range selector use the NP261XHD. Trucks with electronic shift (a push button or knob on the dash) use the NP263XHD.

How tight do I tighten the transfer case mounting nuts at the transmission output adapter?
The factory recommended torque specification is 37 ft-lbs for the transfer case adapter nuts on both the NP261XHD and NP263XHD.

How tight do I tighten the transfer case assembly bolts?
The factory recommended torque specification is 27 ft-lbs for the transfer case assembly bolts on both the NP261XHD and NP263XHD.

I hear a grinding noise at low speed after reassembling my transfer case. What could that be?
A low speed grinding noise is most commonly caused by the rear output bearing snap ring not being fully seated, which lets the bearing move out of alignment. Verify that the snap ring is fully engaged and seated in the rear housing and the locating groove in the bearing.

What would cause a speed sensor correlation code after reassembly?
A speed sensor correlation code often comes with a low speed grinding noise and is frequently caused by the rear output bearing snap ring not being fully seated. Verify that the snap ring is fully engaged and properly seated.

Does this kit include bearings?
No. This kit includes seals, O-rings, the grommet and the adapter gasket only. For bearings too, see the Transfer Case Bearing and Seal Kit, 263XHD.

For warranty information, see our Warranty Policy.