I have bone stock 06' 4x4 F-150. Recently it has a noise that usually sounds like a tin can getting scraped or something rolling around in it. Mostly does it only while applying gas. Took it to shop after it became a squeal and they replaced front bearing. Got it back, still had same small noise but no squeal. Began squeal again shortly and they replaced front diff. Small noise resumed after a couple of days again only under "gas". Squeal returned again so bearing and outer "engaging teeth" were replaced. 2 days later the squeal comes and goes. Low speed has a clicking sound. Still continues to have the tin can sound while giving the gas. Any ideas?