I hold the Rally Pack Register for the past 30 years (when I created it). There aren't many on it as most cars you see aren't actually GS Rally Packs but opted Rally Pack extras on a GL made more confusing that both are stamped GLs. British codes and Australian ones are completely different. If you can send me a image of the compliance plates that would be good. One hurdle though is you need to make a few posts I think before you can privately message. Don' t post the plate pics publicly send them to me in a private message. But feel free to post images of the car in this thread would be helpful to start with and of the engine bay inner right hand guard. Can you start by telling me what month in 79 it is? Because the Plate ID says GL because Rally Packs use a GL shell as all Australian shells are strengthened that is not a clear indicator if its a genuine Rally Pack or not. That requires an in person inspection or the Certificate from Ford Australia if it left the factory as a GS Rally Pack. But with enough photos I can usually tell if its more likely to be one or not.
Raw Orange is the best colour for Rally Packs