Front End Issue

Hi all. I have a 2010 Prostar. While driving at highway speeds (55-70mph) when I hit a bump or go over a rough patch of road I get a violent shaking in my steering wheel. Eventually it stops and I can resume normal driving. Sometimes I have to slow down to stop the shaking. I've gone to my local shop to have the issue checked out. At first they thought I needed to replace my steering shaft. That wasn't it. Then they thought my U joints needed to be changed. That wasn't it. We found some play between one of my tie rods and the cross tube on the driver side. I changed the entire cross tube, both tie rods, and got a wheel alignment. The problem still exist. I went back and had my steer tire checked and speed balanced. Same problem. This is a head scratcher for me.

I took it back to the shop to let them know I'm still having the same issue. They checked again and are now telling me I need to change me steering column. The part alone is $1500. I went to a different shop just to get a second opinion. Of course I didn't tell them what my local guy said. I wanted to see if they would come back with the same diagnosis. They greased the upper U joint on my steering shaft and suggested I change my steering box. Has anyone here experienced any issue like this? I'd be grateful for any insight or suggestions anyone can offer.

 

Forgive me for my ignorance. Towed??

 

I really appreciate the feed back guys. Please keep it coming. Something I forgot to add is that when I twist the steering shaft, I can hear a "jingling" sound coming from the upper area leading into the cab. This is what led me to believe there was an issue with the U joint. Like I said though. The U joints checked out fine.

 

Wouldn't the toe have been checked when they did the alignment?