GMC 2008 Acadia - Manual (Page 138)

Center Console Storage
The armrest on the center console can slide forwards and
backwards by holding up the lever located on the front of
it. To open the armrest storage area, press the button
located on the front of the armrest. There is additional
storage under the armrest. Move the armrest all the way
to the rear position. The tray can be removed for
additional storage.
Second Row Center Console
Your vehicle may have a second row center console.
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