I've done some research on cackle and it does sound similiar to what I'm experiencing. BUT, mine is consistent through out the rpm range which is making me think that I've got a spun rod bearing. I inspected the oil during the last oil change and could not find any flakes or see any signs of metal at all. Need help asap. Could this be the noise of a failing injector? The noise is louder after it's warmed up and I can faintly hear it inside the cab at cruise. I've tried ever program that I have. Scanned the truck for codes. NOTHING. I have heard of guys diagnosing injectors by unplugging the supply for specific injectors while the truck is running. Is that a feasible option. Strapped for cash right now and I have a week to fix this. 3100 mile trip towing a small car through canada.