Chevrolet 1998 C/K Full-Size Pickup Owner's Manual page 317

Transfer Case
When to Check Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant. See "Periodic Maintenance
Inspections" in the Index.
How to Check Lubricant
If the level is below the bottom of the filler plug hole,
you'll need to add some lubricant. Add enough lubricant
to raise the level to the bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule
to
determine what
kind of lubricant to use. See "Recommended Fluids and
Lubricants" in the Index.
Front Axle
When to Check and Change Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant and when to change it. See
"Scheduled Maintenance Services" in the Index.
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