Bought the Silverado LT, 5.3 in 2019, when it had 12,500 on it. It had a chirping sound at idle, sounded like, chirp..........chirp..........chirp as it was idling. Thought it was the belt or an idler pulley. Dealer shop said the thermostat was the culprit, replaced it, sound briefly abated. Started again, took it back in, they said they couldn't hear it. Has not affected the truck in any way, and I now have 58k on it. Chirping is still there at idle, just more obvious. Anyone have a simlar experience, and the cause?