It's mounted to the transmission. Here are directions I found for replacement: Disconnect the negative battery cable.
Raise and support the vehicle.
Remove the catalytic converter Y-pipe.
Unplug the VSS electrical connector.
Remove the VSS protective heat shield.
Remove the retaining bolt from the VSS.
Lift the VSS out of the transaxle.
Remove the driven gear retainer and the drive gear.
To install: Inspect the O-ring on the sensor and replace if necessary.
Install the driven gear and the retainer.
Place the VSS into the transaxle.
Tighten the retaining bolt to 36-53 inch lbs. (4-6 Nm).
Install the VSS protective heat shield.
Attach the VSS electrical connector.
Install the catalytic converter Y-pipe.
Lower the vehicle.
Connect the negative battery cable.