GMC 2010 Yukon/Yukon XL Owner's Manual page 406

Two-wheel-drive vehicles and four-wheel drive vehicles
with a single speed automatic transfer case should
not be towed with the rear wheels on the ground.
Two-wheel-drive transmissions have no provisions for
internal lubrication while being towed. Four-wheel drive
vehicles with a single speed automatic transfer case
have no neutral position and will spin the transmission
when the rear wheels turn.
To dolly tow a two wheel drive vehicle or a four-wheel
drive vehicle with a single speed automatic transfer
case, the vehicle must be towed with the rear wheels
on the dolly. See Rear Towing (Rear Wheels Off the
Ground) later in this section for more information.
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