If it sounds like a howl/rub it might/could be the steering rack. I have it on Right returns. It turns out it is just a resonance in the lines. There is a TSB on it, they put in a different return line on it, and it minimizes it a bit. I found it helped also to put Mobil 1 ATF in the rack. Drips a bit by the seals, but well worth it.
