OK all, i'm needing the help and experience of you guys on this one. As the title says, my 2010 has developed a intermittent growling sound/slight vibration once i reach around 45-50 mph. It is like clock work and will happen every time. It surges in and out when driving and holding any speed over 45 mph or even accelerating for that matter. I just replaced both front wheel bearing/hub assemblies, and this did not fix the issue. As i drove today, if I had to try to isolate the sound, it miiiiight be coming from the rear of vehicle but really hard to say. I also recently replaced the rear differential fluid with BG 75w90. This issue started up a couple months after doing a 3" lift and installing larger heavier tires, thus making me think it could have been the wheel bearings going bad, etc. I had one person state that I should drain rear differential fluid and go to a 75w140, to add thicker viscosity. I really just don't know the route to take on this one and trying to avoid taking to a shop if I don't have to. Thank you in advance.