GMC 2014 Yukon/Yukon XL Owner's Manual page 26

Vehicles with a two
speed transfer case have a
N (Neutral) position. Shift the
transfer case to N (Neutral) only
when towing the vehicle. See
Recreational Vehicle Towing on
page 10-81 or Towing the Vehicle
on page 10-80.
See Four-Wheel Drive (Single
Speed Automatic Transfer Case) on
page 9-37 or Four-Wheel Drive (Two
Speed Automatic Transfer Case) on
page 9-33.