I had a battery fail in my 2003 olds alero (6 cyl), replaced it, then my alternator failed (bosch), replaced that now the new alternator failed after 2 days why?
If this is a rebuilt alternator from a nationwide parts store, it is not uncommon for these to fail. Take it back to where you bought it and get a replacement. I hate to say it, but it's one of those things. You can purchase a new one from GM and it has the possibility it will fail in two days. Some things just cannot be tested well enough coming from the factory or rebuild site. You put them under load for a period of time and they fail. No rhyme or reason. If it fails again in a short period of time, I'd take it back, get my money back, and go to a different source to purchase a new one.