If you DO find the person/persons responsible......shoot them!
If I had a vintage vette, with a cap worth quite a bit, you can bet that somewhere on that cap there would be an identifying mark of some sort. 2 tick marks on the inside edge or something.
Matter of fact, the caps stolen might just have a mark somewhere that is logged and easily identifiable as the owners. So to those who stole the caps, and you know you will try and sell them, that little mark that looks like a scratch is just a scratch, and not something that will get you busted and thrown in jail where Leroy will arserape you like the beoch you are!