S took AP AB Calc test, but he also took the USC math placement test in April, because he thought his AP scores would not be back in time for orientation (last week.) From what S said, I understand that the USC placement test only is for placement into Calc I or lower. It will not place you into Calc II, Vector Calc, etc. They use AP scores for that. Again, that is what I understood, but your advisor could help you out on that when you go for registration. Son's advisor wanted him to go ahead and register for Calc II. Have you thought about auditing the class instead of re-taking it? Then you could still use your credits to go into vector calc.