i have a chevy 350 transmission that makes a rattling noise going down the highway but it will quit if i drop it to the next gear down. it shift out fine and drive fine but just makes that rattling noise. i say it the tranmission because this happened after i got down on it and sound like it came out of gear and thats when i noticed the rattling. other than the rattling it runs fine. please help if you have any ideas!!!!!