My local autozone has the metal ones. What year car do you have? The 97/98 had a tensioner that has the lower elbow cast into it. These can break... That is prob why they mentioned it. There is always markup on parts when you go to a shop. Which is also why if you don't like the price tell them and they will most likely work with you to get the price down. But if you can do the work yourself, it is always cheaper. Keep in mind the plastic elbows do break inside the lower manifold and need pryed out... Good luck
home depot or lowes, buy a 30 piece 6 sided socket set. 30 bucks tops. they come metric and standard in the kit. its pretty much all you need to do most maintenance on a w body.
not really. put a socket on the pulley bolt on the tensioner, then turn the nut so the pulley moves away from the belt, once you figure out what way to turn it slide the belt off the alt pulley.
you may need a small pipe ( or breaker bar) to hold the tensioner in place, its damn tight, leverage is your friend.