GMC 2006 Canyon - Manual (Page 324)

If the level is below the bottom of the filler plug hole,
located on the front axle, you may need to add
some lubricant.
When the differential is cold, add enough lubricant to
raise the level to 1/2 inch (12 mm) below the filler
plug hole.
When the differential is at operating temperature
(warm), add enough lubricant to raise the level to the
bottom of the filler plug hole.
What to Use
See Recommended Fluids and Lubricants on page 6-13
to determine what kind of lubricant to use.
Bulb Replacement
For the proper type of replacement bulbs, see
Replacement Bulbs on page 5-52.
For any bulb changing procedure not listed in this
section, contact your dealer.
Halogen Bulbs
{ CAUTION:
Halogen bulbs have pressurized gas inside and
can burst if you drop or scratch the bulb. You or
others could be injured. Be sure to read and
follow the instructions on the bulb package.
5-48