GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 GMC Sierra Denali 🢒 Transmission/Transaxle 🢒 Clutch 🢒 Transmission Disassemble

Tools Required

    • J 8614-01 Flange and Pulley Holding Tool
    • J 23907 Slide Hammer with Bearing Adapter
    • J 36825 Output Shaft Oil Seal Remover - 4WD Models Only
    • J 44707 T-Bar Push Puller
    • J 44725 Gear Pack Assembly Fixture
    • J 44726 2/3 Jaw Puller
    • J 44730 Intermediate Case Puller Legs

    Object Number: 661219 Size: SH
  1. Remove the drain plug and drain the transmission fluid.

    2. Object Number: 661221 Size: SH
  2. Position the transmission on the floor with the output shaft up. Use boards in order to allow for the protrusion of the input shaft.
  3. If the transmission is equipped with a power take-off (PTO), remove the PTO.

    4. Object Number: 661223 Size: SH
  4. Remove the shift control housing bolts.
  5. Remove the shift control housing assembly.

    6. Object Number: 727452 Size: SH
  6. For RWD transmission, using the J 8614-01 , loosen the propeller shaft yoke nut.

    7. Object Number: 661231 Size: SH
  7. For RWD transmission, remove the propeller shaft yoke nut and discard.
  8. Remove the propeller shaft yoke.

    9. Object Number: 661234 Size: SH
  9. Remove the shift shaft detent sleeve and the shift shaft detent plunger.

    10. Object Number: 663712 Size: SH

    Notice:  Do not nick, scratch or damage the sealing surface. The sealing surface is a machined surface. Damage to the machined surface can cause leakage.

  10. If RWD, remove the vehicle speed sensor (VSS) bolt and washer.
  11. Remove the VSS and O-ring seal.
  12. Remove and discard the O-ring seal.

    13. Object Number: 661233 Size: SH
  13. Remove the 19 bolts retaining the rear case to the front case.

    14. Object Number: 661236 Size: SH

    Important: Do not separate the rear case from the intermediate case by using a pry bar between the cases. The cases have machined sealing surfaces.

  14. Remove the rear case.
    15. • Use a soft-face hammer and hit up on the rear case.
    • The cases should come apart once the sealer is broken.
    • There are 2 dowel pins that may bind in the rear case.
    • The mainshaft rear bearing is a slip fit in the rear case and may bind if the case is not lifted up straight.

    Object Number: 661237 Size: SH
  15. Remove the 2 bolts for the intermediate case.

    16. Object Number: 661238 Size: SH
  16. Install the S-hooks in the webbing of the intermediate case to the locations shown.

    17. Attach a suitable chain to the S-hooks.


    Object Number: 661239 Size: SH
  17. Using a suitable lifting device, carefully remove the gear assembly from the front case.

    18. Object Number: 661249 Size: SH

    Important: The weight of the gear assembly is extended over the edge of the workbench. The weight may tip over or overload a standard metal workbench.

  18. Secure the J 44725  (1) to a sturdy workbench.
  19. Position the gear assembly on the J 44725 .

    20. Object Number: 661258 Size: SH

    Notice: When removing the roll pins from the shift shafts use a punch that is a slightly smaller diameter than the roll pin. Flaring of the shift shaft groove may occur if the punch binds. This will result in extra effort to remove the shift forks or shift control levers. When double roll pins are used, remove both of the roll pins at the same time. Support the shift component when removing the roll pins to prevent damage to the shift shafts. Do not reuse the roll pins after removal.

  20. Using a hammer and punch, remove the roll pins from the internal shift control rear lever.

    21. Object Number: 661975 Size: SH
  21. Remove the internal shift control rear lever.

    22. Object Number: 661262 Size: SH
  22. Using a hammer and a punch, remove the roll pins for the internal shift control front lever.

    23. Object Number: 662001 Size: SH
  23. Remove the internal shift control front lever.
    24. 23.1. Turn the internal shift control front lever in order to clear the 2nd/3rd shift fork and the 4th/5th shift fork.
    23.2. Remove the shift shaft with the internal shift control front lever.

    Object Number: 661994 Size: SH
  24. Using the J 36825  (1) and the J 23907  (2), remove the 4 shift shaft detent plugs.

    25. Object Number: 661996 Size: SH

    Important: Only remove the plungers as needed for replacement.

  25. Remove the shift shaft detent springs and the shift shaft detent plungers. The plungers should only be removed if replacing the plungers. The plungers may be hard to come out now. After removing the shift shafts, the plungers will be easier to remove.

    26. Object Number: 663682 Size: SH

    Notice: When removing the roll pins from the shift shafts use a punch that is a slightly smaller diameter than the roll pin. Flaring of the shift shaft groove may occur if the punch binds. This will result in extra effort to remove the shift forks or shift control levers. When double roll pins are used, remove both of the roll pins at the same time. Support the shift component when removing the roll pins to prevent damage to the shift shafts. Do not reuse the roll pins after removal.

    Important: The 4th/5th shift fork and the 2nd/3rd shift fork do not require removal from the shift shafts for transmission disassembly. Do not remove the roll pins from the 4th/5th shift fork and the 2nd/3rd shift fork unless replacing the shift forks or the shift shafts.

  26. Remove the following roll pins:
    27. • The 6th gear shift fork (1)
    • The 1st/reverse gear shift fork (2)

    Object Number: 662003 Size: SH
  27. Remove the 6th gear shift fork and shaft.
    28. 27.1. Move the interlock plate in the 6th gear position by moving the plate toward the 1st/reverse shift shaft.
    27.2. Pull up on the shift shaft while tapping down on the shift fork with a soft-face hammer.
    27.3. Remove the shift fork and shaft from the 6th gear synchronizer assembly.

    Object Number: 662004 Size: SH
  28. Remove the 1st/reverse shift fork and shaft.
    29. 28.1. Move the interlock plate in the reverse gear shift position by moving the plate toward the 6th gear shift shaft.
    28.2. Pull up on the shift shaft while tapping down on the shift fork with a soft-face hammer.
    28.3. Remove the shift fork and shaft from the 1st/reverse gear synchronizer hub.

    Object Number: 722214 Size: SH
  29. If 4WD, remove the retaining ring for the mainshaft rear bearing.

    30. Object Number: 662005 Size: SH
  30. Using the J 44726 , remove the gears from the mainshaft.

    31. Object Number: 662006 Size: MH
  31. Remove the following components from the mainshaft:
    32. 31.1. The speed sensor reluctor wheel, RWD only (1)
    31.2. The mainshaft rear bearing (2)
    31.3. The reverse gear thrust washer (3)
    31.4. The reverse gear (4)
    31.5. The reverse gear bearings (5)
    31.6. The reverse gear bushing (6)
    31.7. The reverse gear synchronizer blocking ring (7)
    31.8. The 1st/reverse synchronizer assembly (8)
    31.9. The 1st gear synchronizer blocking ring (9)
    31.10. The 1st gear (10)
    31.11. The 1st gear bearings (11)

    Object Number: 662008 Size: SH
  32. Remove the retaining ring for the 6th gear.

    33. Object Number: 662009 Size: SH
  33. Remove the following components from the countershaft (4):
    34. 33.1. The thrust washer (1)
    33.2. The 6th gear (2)
    33.3. The 6th gear bearing (3)

    Object Number: 663713 Size: SH
  34. Remove the bolts for the shift interlock plate.
  35. Let the shift interlock plate rest on the shift shafts.

    36. Object Number: 662010 Size: SH
  36. Install the J 44730  (2) to the J 44707  (1).

    37. Important: You will be using the intermediate case to pull off the 6th gear synchronizer hub and the 6th gear bushing. Ensure the J 44730 is properly located on the intermediate case.

  37. Install the J 44730  (2) on the intermediate case as shown. The J 44730 needs to be aligned in order for the J 44707 to be centered on the mainshaft.
  38. Using the J 44730  (2) and the J 44707  (1) on the countershaft, remove the 6th gear synchronizer hub and 6th gear bushing.
    39. • The intermediate case will slide off the 2nd/3rd shift shaft and the 4th/5th shift shaft.
    • Keep the shift shafts straight in order to ensure the intermediate case does not bind on the shift shafts.
    • If the intermediate case starts to bind on the shift shafts, stop pulling.
    • Straighten the shift shafts in the intermediate case and continue pulling.

    Object Number: 662012 Size: SH
  39. Remove the 6th gear bearing race (1).
  40. Remove the 6th gear synchronizer assembly (2).

    41. Object Number: 662019 Size: SH
  41. Remove the intermediate case from the mainshaft and the countershaft.

    42. Object Number: 724133 Size: SH
  42. Remove the 6th gear spacer from the countershaft.

    43. Object Number: 663680 Size: SH
  43. Remove the 2nd/3rd shift fork and shaft, the 4th/5th shift fork and shaft, and the shift interlock plate from the mainshaft assembly.

    44. Object Number: 662020 Size: SH
  44. Remove the countershaft from the mainshaft by walking the countershaft away.