National 99170 Differential Pinion Repair Sleeve - Front Outer or Rear Outer

National 99170 Differential Pinion Repair Sleeve

National 99170 is a stainless steel differential pinion repair sleeve for rear outer applications on a wide range of GM axle setups. It is sized for a shaft diameter of 1.739 in. to 1.742 in. and is used to restore a worn sealing surface at the pinion area.

Key Features

• Stainless steel construction for corrosion resistance
• Repair sleeve design for differential pinion seal surface restoration
• Shaft size: 1.739 in. to 1.742 in.
• Overall width: 0.500 in.; width on shaft: 0.375 in.
• Flanged outside diameter: 2.063 in.
• Installation depth: 0.813 in.
• National 99170 cross-references Timken KWK99170 and 99170RS

Detailed Description

This National repair sleeve is built for driveline service where the pinion seal rides on a worn or grooved shaft surface. By providing a precise stainless steel sleeve, it helps restore the sealing area without replacing the entire shaft assembly. National has focused on premium sealing solutions for more than 75 years, and this part reflects that experience in a repair-focused design for older Chevrolet, GMC, Buick, Pontiac, Oldsmobile, and related GM vehicles.

Compatible applications include rear outer service on models such as Chevrolet C10, Chevrolet K5 Blazer, GMC Jimmy, Chevrolet Camaro, and Pontiac Firebird when the listed axle and differential notes match. National 99170 is also referenced for many GM trucks, vans, and passenger cars using 8.875-inch ring gear GMC axle differential pinion seal applications.

What It Helps Fix

• Grooved or worn pinion seal contact surfaces
• Oil seepage at the differential pinion seal area
• Seal wear caused by shaft surface damage
• Repeat leaks after prior seal replacement
• Restoration needs on older GM rear axle assemblies

Installation Notes and Tips

Verify shaft diameter before installation: 1.739 in. nominal, with a minimum of 1.736 in. and maximum of 1.742 in. Confirm the axle, ring gear size, and differential notes against the vehicle listing before ordering. This part installs to a depth of 0.813 in. and is intended for rear outer pinion seal repair service. For fitment examples, it is listed for Chevrolet C10, rear outer; GMC Jimmy, rear outer; and Pontiac Firebird, rear outer in the specified applications.

Quality Assurance

National designs sealing components for modern and legacy driveline service, with a long history in the aftermarket. Part number 99170 is engineered as a repair sleeve for differential pinion seal applications and is backed by National’s established sealing product expertise.