Save yourselves the hassle of removing the ECU to find out the code.
Stop in at your nearest Supercheap and pick up a telescopic inspection mirror. I grabbed one on the way home for $9.99.
http://img148.echo.cx/img148/5787/in...nmirror7eg.jpg
Use a torch to illuminate the ECU and work the mirror up between the side of the ECU (which faces the front of the car) and the centre tunnel so you can read the numbers off (they'll be backwards obviously) and have a helper write the numbers down for you as you read them out.
Simple painless and done in less than 5mins :)
Oh and I believe the number you'll be looking for is above the barcode. My May 2004 build ECU number is: 37820-RBB-
Ö01 (Ö=O for Oz :p )