GMC 2009 Savana - Manual (Page 229)

All-Wheel-Drive Vehicles The vehicle was not designed to be towed with two
wheels on the ground. To properly tow these vehicles,
they should be placed on a platform trailer with all
four wheels off the ground.
Notice: Towing an all-wheel-drive vehicle with all
four wheels on the ground, or even with only two of
its wheels on the ground, will damage drivetrain
components. Do not tow an all-wheel-drive vehicle
with any of its wheels on the ground.
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