I have a 1994 F450 with a 7.3. Driving it the other day and get her up to about 25mph all of a sudden the truck starts shaking like CRAZY! I thought I was going to lose control and die. It was bad! Happened again on the way back. Each time it happened the steering wheel alignment moved. The steering wheel was straight before it happened the first time. After the bouncing it was about 45 degrees off center to the right but the wheels were straight. Next time it moved again and ended up almost completely vertical with the wheels straight. Can this be anything else but the steering box?