Recently a strange humming noise/whine has been coming from somewhere beneath my truck (the crewcab) and I'm not sure what it is. It sounds like metal scraping on metal, and it only occurs when applying power (i.e. not when coasting). It has been speculated that it is my tranny but it seems to be functioning normaly. I put some of the magic Lucas stuff in it and did not affect the noise at all. The noise is unbearably loud and doesnt seem like its going to go away on its own so anyone have any ideas on things to look for or cheap items to try replacing? The truck has 170k on it and has a 4L80E 4 speed auto tranny. Its possible that this is the original tranny in the truck, and if thats the case it has had a long, hard life.