How do you replace the alternator on a 1991 Chevy Cavalier?

Remove the alternator restraint bracket screws. Next, using a 15mm wrench turn the tensioner bolt located on the left side of the engine block (The side where the pulley assembly is). Turn just enough to push back and down. The tensioner should move loosening the belt and freeing the tension from the alternator. Then, remove all of the screws securing the alternator. Disconnect the electric ground cable from the rear of the alternator. Remove the alternator. Installing the new one is basically the reverse of the uninstall. Remember** Don't fight with the belt. If it's too tight to put around the alternator loosen the tensioner. If you can't get the belt all the way over the alternator pulley, put it as far as you can and stabilize it with a pry bar. While holding the belt partially on the alternator pulley with the pry bar, have someone responsible bump the ignition. Do not turn the car on! Barely turn the key till the starter tries to turn. The belt should have jumped on now.