Glenn,
If the truck body has iron in it, I don't think it's possible to make it non-magnetic. If this has truly happened somehow, patent it pronto...many industries would love to utilize this trick.
Keep us posted on the rest of the story. Although it seems like this is whats happening, I don't see how it's possible. It's the properties of the little magnets that do the "sticking", they just need something ferrous to attract to.
I think this is right!
Stuart
