Hmmm,......different part numbers.
Not sure what the difference is,....could be the connectors,....the mounting,....the ampere rating,....dunno,sorry.:dunno
**edit**
Ah,...the '03-'03 unit has 7 wires,while the '06< has 8.Dont know what the extra black wire is,...have'nt got a decent clear wiring diagram.Might just be a neg/earth,....but dont quote me on that!!