transmission grinding

I’m driving and auto ecoboost and whenever I’m at a red light I hear and feel vibrations. They lower when the AC is off and vanish completely when I put the car in neutral... any ideas what’s going on?

Please look at the following photos for clarification. Please Inspect Your Mustangs ASAP. This is the feed line from the brake master cylinder to the clutch master cylinder. This is a quick disconnect fitting/line assembly. If any of you are familiar with Truck Air Brake Systems, Industrial...