Hi, I hope that someone could guide me in the right direction on this issue. I have a 2007 ford edge SEL AWD with about 150,000 miles on it and it's starting to make some knocking noise from the rear whenever I accelerate hard. When I come to a complete stop, ease on the gas to move, the knocking goes away until I reach about 20mph. I hoping that is not my diff because I heard that would cost a lot of money to replace. I did a little research and came upon this video https://www.youtube.com/watch?v=OwrH2kBoyhw. Is this the right direction that I should be looking into in getting this issue fix or should I be looking into something else that could be causing the knocking noise?