Chassis greasing should be performed every 6 months or 7500 miles for trucks used in normal/light service. More frequent greasing is recommended for trucks in heavy/severe usage; about every 3 months or 3000 miles. Greasing can be performed with a commercial pressurized grease gun or at home by using a hand-operated grease gun. Wipe the grease fittings clean before greasing in order to prevent the possibility of forcing any dirt into the component.
The four wheel drive front driveshaft requires special attention for lubrication. The large constant velocity joint at the front of the transfer case has a special grease fitting in the centering ball. A special needle nose adapter for a flush type fitting is required, as well as a special lubricant (GM part No. 1052497). You can only get at this fitting when it is facing up toward the floorboard, so you need a flexible hose, too.
Water resistant EP chassis lubricant (grease) conforming to GM specification 6031-M (GM part No. 1052497) should be used for all chassis grease points.