I have a 95 3500 with 95k miles. I just hit a rough stretch of road (wash board) at about 65 miles/hr and the front end started violently shaking and would not stop until the vehicle was almost stopped. The same thing happened last year about this time and I replaced the stearing shock absorber. Evendently didn't fix the problem. Any ideas as to what is causing this? I is extremely dangerous when this happens.