GMC Sierra 3500HD 2001 Owner's Manual page 258

Scheduled Maintenance
Long Trip/Highway Intervals
Every 50,000 Miles (83 000 km): Automatic
Transmission Service.
Every 60,000 Miles (100 000 km): Engine Accessory
Drive Belt Inspection. If Equipped: Exhaust Gas
Recirculation System Inspection. Gasoline Engine
Only: Evaporative Control System Inspection.
Diesel Engine Only: Crankcase Depression Regulator
Valve (CDRV) System Check.
7-8
Long Trip/Highway Intervals
Every 100,000 Miles (166 000 km): Gasoline Engine
Only: Spark Plug Wire Inspection. Gasoline Engine
Only: Spark Plug Replacement. Gasoline Engine
Only: Automatic Transmission Service (normal
conditions). Gasoline Engine Only: Positive
Crankcase Ventilation (PCV) Valve Inspection.
Every 150,000 Miles (240 000 km): Cooling System
Service (or every 60 months, whichever occurs first).
These intervals only summarize maintenance services.
Be sure to follow the complete scheduled maintenance
on the following pages.