most tyre outlets will have them or can get them... they are illegal at least in victoria but what the hell. You may have balancing problems. The spacer is going to be *very* thick. Another problem you may get ( and I am not sure ) is the offset of the wheel may make it very hard to fit it under the guards depending on the car.
I enquired about this at the Summernats with the guy at the Momo stand (didn't want the Momos , just wanted to find out if AUXR8 wheels fit onto EB). He quoted me around $200 per spacer, said they have to be specially imported from Europe. Sounds like BS to me. Any machine shop should bhe able to tur nsome up out of alloy or steel for a fraction of that price. I can't remember how thick they have to be, could be 25mm, maybe more. You might have to get longer wheel studs as well. Could throw all the suspension geometry out as well causing more problems.
There is two ways to do it the safe and legal way and the cheap and nasty way.
One thick or a couple thin spacers is the cheap and nasty way, not to mention illegal and if you want your AU XR8 wheels to come off while your driving thats the way to go.
OR, the spacer bolts onto your existing stud pattern and a new S/P is made in the spacer with new studs. So your stud lenth (Ha Ha sorry) stays the same. Also the this is how you fie AU wheels on Cortina's, I've seen it done..
GruppeA wheel spacers are normally 25mm, however I do make 30mm and other measurements on request. Price varys according to width. They're fully engineered and certified, and yes they are illegal in some states. They aren't wheel spacers, they're actually wheel extensions, complete with studs.
When I was getting new rims for my car, I was looking at some sets for AU's.. I enquired about the wheel spacers, and was told by 3 different places that a 40mm spacer was required to fit an AU rim to a pre AU falcon. (yes - 40mm !!) prices ranged from $20 each to $45 each.
I ended up going for the cheaper option and just buying a set of 18's to suit a pre AU falcon.