Hi chaps, I'm hoping someone here can help me with an issue I'm having on my Puma I fitted an ATB in the rear of my Puma in October 2017, and recently started noticing a groaning noise that's becoming quite bad.  My indie and I eventually traced it to the rear diff: at specific rpm/speed, there is a loud, low-frequency groaning noise + vibration emanating from the rear of the car. It almost feels as if the seats have built-in massage function, especially when I hit 80-100kmh.