How do you put the alternator back on a 91 Dodge Spirit that has a spring loaded tensioner?

Install everything back on the car except for the alternator belt. You are going to need a long socket bar and a 15 mm socket. A socket bar is basically a rachet without the rachet mechanism. It has the square end on it to go into the socket at a 90 degree angle. Set up the belt on all the pulleys except for the alternator. Put the socket and bar on the bolt that is holding the tensioner on and twist it like you were tightening it. This will move the tensioner and give you slack so you can put the belt onto the alternator pulley. Once it's on and aligned, slowly ease off the bar until the belt goes tight. Remove the socket and bar and you are done.