Where is the VSS located?

For the OP, who no longer needs this information:
1995-1997 have mechanical speedometers, the VSS is in the speedometer.

For the thread revivist:
1998-2023 have electronic speedometers, with the VSS signal coming from various sources, depending on year and options. For your 2005, the speed signal is calculated by the ABS ECU, which is output to the gauge cluster, where it is then output to the rest of the systems in the truck. It's not a single sensor, it is based on more than one sensor.

Jeff