Hi, I have a 2002 trailblazer LTZ and it is making a small vibration/ slight grinding metal on metal noise. The sound only happens while it’s driving 35 to 40 MPH or higher. It stays the same sound reguardless of rpm Just a slight low growl driving. It is not the wheel bearings, has anyone had the same issues and could possibly tell me what the issue could be? It seems to be near the back end of the motor or near transmission but I’m not sure. It is a 4x4 and the transmission has been changed out for a newer one. I just bought the vehicle so I’m not sure if it was happening before. Any ideas where to start first?