GMC 2010 Sierra - Manual (Page 517)

Manual Shift Transfer Case
A. Fill Plug
B. Drain Plug
Active Transfer Case
A. Fill Plug
B. Drain Plug
To get an accurate reading, the vehicle should be on a
level surface.
If the level is below the bottom of the filler plug hole,
located on the transfer case, you will need to add some
lubricant. Add enough lubricant to raise the level to the
bottom of the filler plug hole. Use care not to
overtighten the plug.
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