Any wrecker should be able to supply them. New they would cost heaps. If you have the old ones you could go to Enzeds or similar and they will make one for you on the spot....but my first stop would be the wreckers.
Wreckers, or check ebay for wrecked commodores and ask for the parts there too, check the f/s section here for cars being wrecked out, may get them there too. Also put an add in the WTB section here too. http://forums.justcommodores.com.au/parts-other-items-sale/159774-wrecking-vq-statesman-5-litre.html
Have a look at the pics of the engine bay here, an see if they are the same looking.
Theres also a vs wrecking in there too, but i think they are different. Remeber if the lines are close and have the same ends, they bend real easy to mate them up. They are a very soft pipe.