my dad's 700r4 makes a buzzing sound when shifted out of park for a few seconds and is making a metallic rubbing noise when under acceleration. Got any ideas?

none?

I had one that made similar noises, the flexplate was rubbing the plastic dust shield. Take it off (if you have one) and see what happens.

The dust shield has been gone. You can feel the vibration on the pan when you hear the noise.

Repaired a groung wire and the buzzing stopped, the rubbing noise was the starter gear hitting the flex plate, WD40 fixed it.