There has become a problem with Mexican issues. Not only with Black Sabbath, but also with lots of other artists. It is popping up so called Radio Station promos with different homemade sleeves. These are ALL FAKE. Usualy these issues comes with the regular singles and lps. And sometimes with fake  labels glued over the original one. If you have one of these, check the matrix number and you'll discover that it is identical to the regular issue.  
If you know that any of these listed below are so, please let me know, and I remove them to that site. Hopefully there is Mexican collector out there, which can help us. All these I have listed here, I think is the real stuff. But are not 100% sure.