hey, i have this popping sound on my tj when i move off. its not loud but a soft low pitch popping sound. If i move off really slow it does not sound. but if i move off normally,not hard, it pops twice. my jeep runs perfectly after it pops and while it pops. I know its not my rear u joint because i just replaced it and it was making that sound before i replaced it and the front u joint looks good. ANY ADVICE?