Martinmace -
You can only check the components to see what you actually have fitted:

1, ECU - What type do you have? - 2wd L6 is mounted behind the blanking panel in the passenger side dash, it will have 2 mounting lugs either side of the connector to bolt it onto the carrier slide.
4x4 one is mounted behind the glovebox, along with the ABS controller. The L8 4x4 ECU doesn't have mounting lugs on the front, it is plain square and just clips into it's mounting position.

2, Wiring loom - 4x4 loom has 3 large multiway connectors on the bulkhead just above the engine, 2wd doesn't.

3, Throttle Position Sensor (TPS) - mounted on the engine side of the throttle body.. unfortunately the only way to see what is fitted is to remove the throttle body with the TPS attached... 2wd one will have reference number PF01, 4x4 PF09. Either of them could be red or black, so that isn't much of a clue.