Yes, I'm remembering now because it's been so long. When looking for a grill for my '65 Barracuda I ended up with a box full of broken grills, all of which just needed what looked like minor repair.
I brought them down to a great machine shop for repair, looking to fix the best one for myself and perhaps selling the others. We found that most of them were magnesium, but not all of them.
We guessed that perhaps the others were aluminum, or perhaps something mixed. We didn't proceed with anything because we didn't want to start a magnesium fire.
Next, I finally found a good grill at Wildcat Auto Wrecking. When I brought it to my local metal dipper they freaked out because the dip reacted like crazy with it. He handed it back and barked at me to tell him next time when I brought him magnesium.
What I don't have is great way of testing exactly what they're made of in terms of metallurgy. But it looks to be that some are magnesium and others are something else. If you look at them closely without paint you can see that they aren't the world's greatest casting. It could be that the metal they used changed by year or by batch. The ears break very easily and it's hard to bend the parallel lengths back into shape.
I do wish I could tell. But I though it was more important to dissuade anyone from trying to start a nasty fire.
Know what would be cool? Finding a near-perfect example of one and casting a new lot out of aluminum. I don't have access to casting anymore otherwise I wouldn't mind doing it myself.
