Chevrolet 2009 Express Owner's Manual page 10

Three Passenger Seat Shown
The driver side pin has a gray cap with a black "L"
marked on it.
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Three Passenger Seat Shown
The passenger side pin has a black cap with a
white "R" marked on it.
On a four passenger seat, each half of the seat has
a set of pins. The driver side has a set marked "L",
and the passenger side has a set marked "R".
If the vehicle has floor mats, the pins will be located
under a flap that has been cut into the mat.