Vehicles over 8500 lbs were not required to be OBDII compliant until MY2004, when the limit was raised to 14,000 lbs.
If your truck has any data to offer, looking at the connector, the protocol would be J1850 PWM or CAN. If the vehicle was OBD-II compliant, then considering the model year, it would use J1850 for OBD.
Even though the truck is not required to be compliant, you may still be able to get useful data like trouble codes and real time parameters.
What kind of OBD-II interface were you using to connect to it? Your VW and Honda both use the ISO 9141 protocol.