I had thought that , I think the noise was the park pawl ratcheting, and I cant be 100% that the act of putting it in park separated the engine and trans through the valve body, I do think most street automatics do though. The act of putting it in park neutrals out the trans through removing the line pressure by the use of the valving if i recall correctly. I went to school for this years ago, but i never became an auto trans guy I'm a 4 speed guy I know some basics of auto, but don t rebuild them.
