Hello, I just replaced my rear differential. Now I have a spinning metalic noise. It happens mostly when I'm going uphill. Can anyone give me any ideas what it may be? We went through and made sure everything was tightened up like it's suppose to be. It's weird but the only thing I can think to compare the sound to is one of those figit spinners when you spin it really fast. My poor truck has over 227000 miles on it and I just want to keep it going. Any help will be greatly appreciated.