I'm getting strange noise from my tranny. When I switch gears R-N-D and back I hear this metal hitting metal sound. It's not griding, rather something hitting something as the tranny moves from D to R.
I also get this metal rattling sound when going over rough spots on the road. I'm thinking loose tranny mount. Any other ideas?

 

Check your exaust heat shields. Especially the one around the converter. As you shift gears the engine moves slightly as force is applied to the wheels. This could cause your exaust to shift slightly and there's your noise. Same applies to bumps.