NP261HD/NP263HD Reinforced Rear Transfer Case Half, GM

This is the rear (output) case half for the GM NP261 and NP263 transfer case family, cast with extra material in the pump contact area. It is the fix for the failure every GM truck shop knows as pump rub: the transfer case oil pump is not pinned to the housing, it floats on the input shaft, and over time it walks against the inside of the rear case half and grinds a groove into the aluminum. Eventually it wears clean through, the case dumps its fluid on the highway, and the transfer case seizes. A worn case half cannot be repaired, and a fresh standard casting will do the same thing again.

Fits NP149, NP246, NP261 and NP263 transfer cases in both light-duty and heavy-duty versions, which covers a large span of GM trucks and SUVs including Silverado and Sierra 1500/2500HD/3500, Tahoe, Yukon, Suburban, Avalanche and Escalade. Manufacturer part number 261263RHALF-HD. It replaces the corresponding GM, Dorman, New Process, New Venture and Yukon Gear rear housings.

Install it during a rebuild, not as a standalone swap. With the case split, clean the mating surface completely, transfer the rear output bearing and seal (this is the right time for a new bearing and seal kit), set the new housing on a fresh bead of RTV, and torque the case bolts in a crossing pattern. While you are in there, inspect the pump itself and the input shaft splines: if the old pump chewed the housing, the pump face is usually scored too and should be replaced along with the case half. Many builders also add a pump rub repair plate or shield behind the pump for extra insurance.

Ships as the bare rear case half. Bearings, seals, the pump and case hardware are not included.