I was driving down the road and was slowing down and shifted to 3rd. When that happened something sounded like it got loose and started rattling. I put it into 2nd, not as much rattling, but putting into 3rd and 4th the rattling was worse. I'm able to put it in any gear with no hesitation, but didn't apply gas because of the rattling and didn't want to make things worse. Anybody know what could have happened?