Received a belt tensioner and pulley for 2008 6.0 from Rock Auto. The originals with 210,000 miles had significant play. The new ones have a small amount of play. I had already replaced the power steering pump, AC compressor belt, and AC compressor belt tensioner. They are fairly cheap so I went ahead with a proactive approach. I’ll keep an eye on the water pump and alternator. The two belts are new as well. This part of my goal of reaching 300,000 miles.