Tools Required

Important: When installing the new retaining rings in any of the following service procedures, ensure that the retaining rings are properly seated before proceeding to the next service procedure. Always use NEW retaining rings.

1. Install the mounting studs to 29.5-30.5 mm (1.16-1.20 in) in height.



2. Attach the J 45759 to the front transfer case using the adapter studs. All of the assembly procedures can be performed with the case mounted to the J 45759 .
3. Install the J 45759  (2) into the J 3289-20  (1) and secure with the pivot pin.




Important: When installing the input bearing, ensure the printing on the bearing is facing toward the front of the input gear.

4. Using a press, install the input bearing. Ensure the bearing is supported by the internal race.



5. Install the input gear bearing retaining ring.



6. Install the input gear.



7. Install the input gear retaining ring.



8. Install the front output shaft bearing in the front case.

•	The bearing will slide in if it is installed straight.

•	The cage side of the bearing faces the inside of the case.




9. Install a new retaining ring for the front input shaft bearing.



10. Install the front output shaft.



11. Install the front output shaft retaining ring.



12. Install the viscous coupling.



13. Install the mainshaft assembly.




Important: The blue colored link faces up or toward the rear of the case.

14. Install the drive chain and sprockets.



15. Install the driven sprocket retaining ring.



16. Install the carrier retaining ring.



17. Lubricate the planetary carrier sun gear bearing with transfer case fluid.
18. Install the sun gear bearing.




Important: Ensure the spline engages with both the sprocket and viscous coupling cover. The sun gear shoulder will bottom on the sprocket if it is installed correctly.

19. Install the sun gear.



20. Install the sun gear thrust washer.




Important: When installing the carrier assembly, a snap should be felt and heard when the carrier is properly seated.

21. Install the carrier assembly.



22. Using the J 8092  (1) and the J 45549  (2), install the mainshaft rear bearing in the rear output shaft.



23. Install the rear output shaft in the annulus gear.




Caution: The vehicle could roll while in park if the annulus gear becomes disengaged from the rear output shaft. Always install a new rear output shaft to annulus gear retaining ring. Ensure the rear output shaft retaining ring is fully seated in the annulus gear.

Notice: Damage may occur to the viscous coupling if the retaining ring for the rear output shaft to the annulus gear fails or becomes dislodged during vehicle operation. Always install a new rear output shaft to annulus gear retaining ring. Ensure the rear output shaft retaining ring is fully seated in the annulus gear.

24. Install the annulus gear retaining ring.



25. Install the oil pump assembly.



26. Install the speed reluctor wheel retaining ring.




Important: 

•	Always use a NEW speed reluctor wheel.

•	The speed reluctor wheel should just contact the retaining ring.

27. Using a press, the J 45540  (2) and the J 5590  (1), install the speed reluctor wheel until it is just contacting the retaining ring.




Important: Ensure the retaining ring groove on the rear output shaft bearing is facing toward the rear of the rear output shaft.

28. Using a press, the J 45540  (2) and the J 5590  (1), install the rear output shaft bearing.



29. Install the rear output shaft bearing retaining ring.



30. Install the rear output shaft assembly.



31. Using the J 8092  (1) and the J 36370  (2), install the front output shaft rear bearing.



32. Remove the 1st design oil pump wear sleeve from the rear case half.




Important: Ensure the oil pump wear sleeve is properly positioned to the largest lug of the oil pump.

33. Install the 2nd design oil pump wear sleeve (1) to the oil pump (2).




Important: Ensure the O-ring is in place in the oil pump.

34. Install the oil pump tube O-ring in the oil pump.
35. Install the oil pump screen and the oil pump tube.
36. Install the chip collector magnet.

Notice: Apply the proper amount of sealant to the flange when assembling the transfer case. Excessive amounts of sealant can plug the oil pump screen, resulting in internal component failure.

Important: Ensure both sealing surfaces of the front and rear case halves are free of dirt, oil, and cleaning solvent.

37. Apply a 3 mm (1/8 in) bead of RTV sealant GM P/N 12345739 (Canadian P/N 10953472) or equivalent to the front case half.
38. Install the locating pins in the front case half.



39. Align the rear case on the rear output shaft bearing.
40. Install the rear case half.
41. Open the outer rear output shaft bearing retaining ring.

Important: Ensure the rear output shaft bearing retaining ring is seated in the groove properly by prying up on the shaft on the rear output shaft assembly.

42. Lower the rear case on to the rear output shaft bearing.
43. Remove the snap ring pliers.

Important: Ensure the rear case is squarely seated on the alignment dowels when it is installed.

44. Lower the rear case on to the alignment dowels.




Notice: This component is made of magnesium. Proper assembly is required to prevent damage. Ensure the magnesium transfer case housings are properly insulated from all external steel components, or galvanic corrosion will occur. New nylon coated case bolts and aluminum washers must be used. Use only aluminum fill and drain plugs. Use only aluminum brackets under the case bolts. Ensure new seals are installed that have a rubber insulated outside diameter and have no tears or cuts. Extensive damage will occur if there is galvanic corrosion between the magnesium and steel components.

45. Position the brackets to the proper bolt hole.

Notice: Refer to Fastener Notice in the Preface section.

46. Install NEW case half bolts and washers.

Tighten
Tighten the case half bolts to 37 N·m (27 lb ft).




47. Using the J 45380 , install a new rear output shaft bushing.

47.1.

Install the bushing on the finger section of the J 45380 .

47.2.

Install the finger section to the main body of the J 45380 .

47.3.

Position the bushing and tool to the case.

47.4.

Using a hammer and the J 45380 , install the bushing.




48. Using the J 42738 , install the input seal.




Important: When installing the rear output shaft seal, ensure that the drain hole is pointed down at an angle at which the transfer case would be installed in the vehicle.

49. Using the J 37668-A , install the rear output shaft seal.



50. Using the J 43484  (2) and the J 8092  (1), install the front output shaft seal.



51. Install the transfer case speed sensor.

Tighten
Tighten the transfer case speed sensor to 15 N·m (11 lb ft).




52. Apply a thin layer of retaining compound GM P/N 12377901, Canadian P/N 10953504, or equivalent, to the NEW aluminum vent pipe.
53. Tap the NEW aluminum vent pipe into the case; ensure the vent pipe is aligned in the direction shown.




Important: Use only drain and fill plugs made of aluminum. Steel or brass plugs are not compatible with the magnesium case.

54. Install the drain plug.

Tighten
Tighten the drain plug to 20 N·m (15 lb ft).




55. Install the fill plug.

Tighten
Tighten the fill plug to 20 N·m (15 lb ft).




56. Install the access plug.