GMC 2008 Yukon Denali Owner's Manual page 418

2. Remove the wing nut (B) used to retain the tool bag
by turning it counterclockwise.
3. Turn the knob (A) on the jack counterclockwise to
release the jack and wheel blocks from the bracket.
4. Remove the wheel blocks and the wheel block
retainer by turning the wing nut (C)
counterclockwise.
5-80
A. Jack
B. Wheel Blocks
C. Jack Handle
D. Jack Handle
Extensions
E. Wheel Wrench