The tensioner on our cars, IS the upper bracket. You tension the alternator belt by swinging it out and locking it in place. But like I said, its possible to install the alt wrong so you can't use the tensionor nut on the stock bracket. Do you have the threaded section with the nut on it? Its welded to the upper attachment point. If you don't someone has probably made some custom upper bracket with no adjustment. You can't actually bolt the alternator to the motor without some kind of upper bracket, and the stock upper bracket has the tensionor built into it, it is not removable.