Lug Nuts
I think even my Chrysler mini-van uses the same thread and pitch, but uses a 21 mm head. I have seen this type used on Opels (Katheryn McCoy's GT to be precise, until I changed them out for the right nuts) and they seemed to work. But it's not so good to only use one (or three) on a wheel, since they weigh quite a bit more than the 19 mm nut, and might cause a balance issue. So long as they have the right bevel, they should work. But if the bevel is wrong, DON'T use them, since an Opel wheel is "lug-centric" (centered by the lug nut) versus some makes that are "hub-centric" (centered by the center hub).
HTH