If you're feeling adventurous, there's usually a
piece of paper under the carpet that lists all that sort of thing. It's usually under the passenger footwell.
If you're not in the mood for carpet removal, then write down your VIN and get on Facebook and go to the
Holden Australia page. Send them a private message (don't post it on the group page) with your VIN, a copy of your licence and proof of ownership (a receipt from when you bought it, or a copy of your RWC - anything official with your name and the VIN on the same page) and tell them you're wanting the build info for your car. If you're nice, they will give it to you. I've made requests through there before and they're really helpful, have all the info you need and importantly, are free.