6:00 pm headed home after a long work day 3 rd gear - let off gas to come to stop at stoplight and kaboom. followed by black and white smoke and a rapid knocking sound. I think the motor threw a rod or dropped a valve. The ttuck is a 99 3500 with 97,000 miles what should I do take it to Cummins or Dodge? I just had Cummins adjust the valves last week. Any ideas what it might be? It is really bad when the rollback tow truck that picks up your dodge is a Ford Babystroke.