Driving along today then all of a sudden my car appears to sound loud as Im driving along. Smoke starts to appear from under the car. I cant really pinpoint where its coming from. But it sounds like its coming from one of the diffs based on the fact that theres a grinding sounds too. When I put in it gear the car didnt want to idle forward. It would move in reverse for a bit then the grinding sound would come back. When I checked both diffs the oil was fine in there. No oil leak was apparent from anywhere under the car. Im clueless as to what it could be cause the car moves when put in D or R. What other things could I look at that would cause a grinding sound when the car is being driven. Any help is GREATLY appreciated.