I wanted to go for the factory look but the genuine Sportwagon camera can't be bought by itself from the dealer.
After looking around on ebay for a while, I settled on this one :
http://cgi.ebay.com.au/ws/eBayISAPI.dll ... 630wt_1918It was fairly expensive, but the specs looked good for low light conditions, It looked about the same size as the Holden one and didn't add the useless guidelines !
Before installing in the car, I tried it out on the headunit first to make sure it worked. The reversing picture only came up as brief flashes on the screen every second or 2. On a regular tv it gave a crappy picture with video noise and halos around everything.
Putting it on a scope showed a noisy video waveform which the headunit obviously hated.
I sent it back to the seller and got a replacement sent, which worked just as badly. Sent him a video of what it was doing, and he replied "Oh, it's not compatible with Commodore headunits" At least I got a full refund, and the customer service was great !
In the end I found a factory fitted camera and tailgate loom from a wrecked Calais wagon and retrofitted it. This one works perfectly

I'll do a write up in a new thread...