How to Prevent Leaf Spring Shifting?

I doubt its twisted. When I refered to twist what I should have said was flex. The trucks in that video have a lot of frame flex due to the high amount of torque those engines are laying down. A typical truck will see frame flex when taking off or pulling hard but not to the degree you see in that video.

 

That's very true what @AModelCat is saying. It's normal for the frames to have Flex, it's part of how they are designed.

However, it does happen sometimes that the frame gets twisted. If it is a new to you truck then that's always a possibility. You don't know what happened with the previous owners . There was a post on here a while back that a person had a brand new truck and their frame was out of whack.

If it is Twisted there are big truck collision shops that have frame machines that they can straighten them out.

I couldn't tell you if it is or not but just something else to take a look at. And also check that your front axle isn't bent.