50000 MI or 80000 KM

Lubricate
    Steering and Suspension
      Lubricate the front suspension, ball joints, steering linkage, transmission shift linkage, transfer case shift linkage, parking brake cable guides, and brake front axle. Ball joints should not be lubricated unless their temperature is -12 degrees C (10 degrees F) or higher or they could be damaged.
Replace
    Oil Filter, Engine
    Fluid Filter - A/T
      Vehicles with Allison transmission replace the external spin-on filter only. The sump filter is only changed during overhaul. TSB 05-00-90-005.
    Fluid - A/T
    Engine Oil
      Change engine oil and filter as indicated by the GM Oil Life System (or every 10,000 miles 16 000 km, or 12 months, whichever occurs first. Reset the system.