GMC 1996 Jimmy Owner's Manual page 268

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
How to Check Lubricant
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.
If the level is below the bottom of the filler plug hole,
you'll need to add some lubricant.
If
the
differential is at operating temperature (warm),
add enough lubricant to raise the level to the bottom of
the filler plug hole.
If the differential is cold, add enough lubricant to raise
the level to 1/2 inch (12 mm) be.low the filler plug hole.
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