So my bro was driving to work in his 03 duramax 3500 and all the sudden there was a big klunk and the steering wheel shook so he pulled over put it in park and let it sit for a min. then he tried to put it in drive and it made a nasty grinding sound and it sound like it is coming from the rear end. i checked all the fluid and they are all good. and the service brake system thing comes up on the dash. any ideas would be awesome please let me know Thanks