GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC C-Series Medium Duty Truck B7 🢒 Driveline/Axle 🢒 Rear Drive Axle 🢒 Differential Replacement

Removal Procedure
  1. Inspect the rear axle housing for leaks and damage.
  2. Clean the rear axle housing with steam.

    3. Important: Shift the two speed rear axle into LOW range, if equipped.

  3. Apply the parking brake.
  4. Block the wheels.
  5. Remove the rear axle housing drain plug. Refer to Lubricant Change .
  6. Remove the propeller shaft. Refer to the appropriate procedure:
    7. •  One-Piece Propeller Shaft Replacement
    •  Two-Piece Propeller Shaft Replacement
    •  Three-Piece Propeller Shaft Replacement
  7. Remove the rear axle shafts. Refer to Rear Axle Disassemble .
  8. Remove the two-speed shift motor, if equipped. Refer to Two Speed Rear Axle Shift Motor Replacement .

    9. Object Number: 198566 Size: SH
  9. Remove the following components from the differential carrier. DO NOT remove the top two fasteners.
    10. • The washers
    • The bolts
    • The stud nuts, if equipped
  10. Use the following steps in order to remove all the rear axles without a differential lock:
    11. 10.1. Remove the top two fasteners.
    10.2. Remove the differential carrier from the rear axle housing.
  11. Use the following steps in order to remove all the rear axles with an Eaton® Differential Lock (using the air pressure engagement method):
    12. 11.1. Engage the differential lock.
             11.1.1. Using an auxiliary air line, apply 552-827 kPa (80-120 psi) air pressure to the rear differential air shift cylinder air port in order to engage the clutch.
             11.1.2. Support and secure the differential carrier to a floor jack.
    11.2. Remove the top two fasteners.
    11.3. Remove the differential carrier from the rear axle housing.
  12. Use the following steps in order to remove all the rear axles with an Eaton® Differential Lock (using the manual engagement method):
    13. 12.1. Engage the differential lock.
             12.1.1. Install an M12x1.5 bolt, over 38 mm (1.5 in) long, in the air shift cylinder air port in order to engage the clutch.
             12.1.2. Apply a rear axle lubricant to the threads of the bolt in order to facilitate hand tightening.
             12.1.3. Hand tighten the bolt using a socket.
             12.1.4. Support and secure the differential carrier to a floor jack.
    12.2. Remove the top two fasteners.
    12.3. Remove the differential carrier from the rear axle housing.
  13. Clean the rear axle housing and the differential carrier mating surfaces.
  14. Clean the rear axle housing bowl interior using Engine Degreaser GM P/N 1050436 or equivalent.
  15. Dry the rear axle housing bowl immediately using clean cloths. Then dry the rear axle housing bowl using compressed air.
  16. Inspect the rear axle housing for the following conditions:
    17. • Cracks
    • Loose studs
    • Nicks
    • Burrs

Installation Procedure

    Object Number: 198568 Size: SH

    Important: Apply a 3.17 mm (0.125 in) diameter bead completely around the rear axle housing differential carrier mating surface and around each threaded hole and stud. Install the differential carrier and fasteners within 20 minutes (before the silicone sealer sets).

  1. Install the Silicone Sealer (RTV) GM P/N 1052366 or equivalent on the rear axle housing surface.
  2. Install the four temporary alignment studs, if needed.
  3. Install the differential carrier.
  4. Use the following steps in order to install all the rear axles without the differential lock:
    5. 4.1. Support and secure the differential carrier to a floor jack.
    4.2. Install the deferential carrier into the rear axle housing.
  5. Use the following steps in order to install all the rear axles with an Eaton® Differential Lock (using the air pressure engagement method):
    6. 5.1. Engage the differential lock.
             5.1.1. Using an auxiliary air line, apply 552-827 kPa (80-120 psi) air pressure to the rear differential air shift cylinder air port in order to engage the clutch.
             5.1.2. Support and secure the differential carrier to a floor jack.
    5.2. Install the differential carrier into the rear axle housing.
  6. Use the following steps in order to install all the rear axles with an Eaton® Differential Lock (using the manual engagement method):
    7. 6.1. Engage the differential lock:
             6.1.1. Install an M12 x 1.5 bolt, over 38 mm (1.5 in) long, in the air shift cylinder air port in order to engage the clutch.
             6.1.2. Apply rear axle lubricant to the threads of the bolt in order to make hand tightening easier.
             6.1.3. Hand tighten the bolt using a socket.
    6.2. Support and secure the differential carrier to a floor jack.
    6.3. Install the differential carrier into the rear axle housing.

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

    Important: Threads must be clean and free of grease. Apply 272 Threadlocker GM P/N 12345493 or equivalent to the threads of each differential carrier bolt.

  7. Install the following components to the differential carrier:
    8. • The washers
    • The bolts
    • The nuts, if equipped

    Tighten
    Tighten the differential carrier bolts and the nuts to the torques listed in Fastener Tightening Specifications .

  8. After installing the differential carrier, disconnect the auxiliary air line or remove the bolt from the rear differential lock air shift cylinder air port.
  9. Install the propeller shaft. Refer to the appropriate procedure:
    10. •  One-Piece Propeller Shaft Replacement
    •  Two-Piece Propeller Shaft Replacement
    •  Three-Piece Propeller Shaft Replacement
  10. Install the rear axle shafts. Refer to Rear Axle Disassemble .
  11. Install the two speed shift motor, if equipped. Refer to Two Speed Rear Axle Shift Motor Replacement .
  12. Install the rear axle shafts.Refer to Rear Axle Disassemble .
  13. Install the rear axle lubricant. Refer to Lubricant Change .
  14. Remove the wheel blocks.