There's a paragraph or 2 in the manual about how to put the truck in neutral for a tow. There's a release cable under the dash near the parking brake.
Also, if it's 4WD, you can put the transfer case in neutral.
Just found it with Google:
MANUAL PARK RELEASE — 8 SPEED
TRANSMISSION
In order to push or tow the vehicle in cases where the
transmission will not shift out of PARK (such as a dead
battery), a Manual Park Release is available.
Follow these steps to activate the Manual Park Release:
1. Firmly apply the parking brake.
2. Using a small screwdriver or similar tool, remove the
Manual Park Release access cover, which is just above
the parking brake release handle, below and to the left
of the steering column.
3. Using the screwdriver or similar tool, push the
Manual Park Release lever locking tab (just below the
middle of the lever) to the right.
4. While holding the locking tab in the disengaged
position, pull the tether strap to rotate the lever
rearward, until it locks in place pointing towards the
driver’s seat. Release the locking tab and verify that
the Manual Park Release lever is locked in the released
position.
5. The vehicle is now out of PARK and can be towed.
Release the parking brake only when the vehicle is
securely connected to a tow vehicle.