I believe there are 2 13mm bolts that hold the tensoner on. One is above the tensoner and one is below. If your looking at your alternater the pully on the left is jsut a pully with a 16mm long bolt through it. That holds the alternater on. The pully right below that and a little to the left is the tensoner. You cant really see the lower bolt so you ahve to feel around. The top one is right behind the pully.