I have a 2008 Ford Ranger Sport 4.0 Liter 4x4 wit 50k miles. A few times recently, seems to be related to colder temps. While attempting to pull the vehicle out of the garage, I put it in reverse. It seems to engage but doesn't move. The first time this happened, I gave it a little gas and there was a "bang" then the vehicle was able to back out of the garage. This happened a couple of times since then but I didn't give the vehicle gas because I didn't want to damage anything. I tried going from Reverse to Park back to Reverse then drive to reverse. Eventually I will hear something clank in. This seems to only be occurring when backing out of the garage and when it is colder. I have an extended warranty but I know if I take it in, they will not find anything. Going to have to do it eventually anyway. Any ideas about what is happening here?