When my truck is at an idle, there is a rattle comming from what sounds like the front of the tranny area. At first i thought it was the cat, but it only does it at low rpms. It runs fine and doesnt do it while being driven, just at an idle or driving very slow. Seems like it started after a trip to the hills, a buddy and i came to a steep road with a tree across it, his jeep was able to turn around, i had to back down, not relizing i was in drive, started to roll backwords, and the truck died. Then took a while to start. Any ideas??

 

Does it still shift OK? Probably just a heat shield buzzing....... can you make it do it while stationary? If you can, go lookin' for it.