GMC Sierra Denali 2006 Owner's Manual page 333

To replace the windshield wiper blade assembly do the
following:
1. Lift the wiper arm away from the windshield.
2. Push the release lever (B) to disengage the hook
and push the wiper arm (A) out of the blade (C).
3. Push the new wiper blade securely on the
wiper arm until you hear the release lever click
into place.
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