I have A 1991 gmc sierra 1 ton dually, when acelarating from a dead stop there is a ringing sound until u reach 10 mph or so then it stops then when it reaches 50 mph or more there is a vibration of some sort when you take your foot off of the gas Ive changed the u-joints, changed the gear oil in the rear end, the sound is kinda like a chatter, the ringing sound at low speeds dosnt sound like its from the same place as the chatter but i cant really tell