This was a simple replacement and perfect for the stock tensioner on the 06 Silverado, 5.3 FlexFuel with 145A alternator. Part of AC Delco made in Canada (at least that one was). All it took was a 15 socket, a 3/8 ratchet and a short extension. Save the bolts before removing the original tensioner. A NOTICE. Remember which screw comes from which position, they are not all the same length (at least on my car). Also, do not over-tighten when re-tightening.