Annoying squeak video

I have a annoying squeak that I've had since I've bought the truck about 8000 miles ago. It occurs when I turn into driveways and sometimes when I go over bumps. It doesn't happen if I'm just driving on a gravel road.

The sound sounds like it's coming from the rear. I don't know enough to know if it's the leaf springs or something else. In the video I'm turning back in forth on a level road.

https://vimeo.com/142027935

 

I tend to get a pretty gnarly squeak that would happen whenever you gave it gas, made a turn, got in, etc. Thing sounded like the typical bed squeaking when having sex sound. Im like 99.99% sure it was the leaf springs, it would happen usually after some good off roading and would go away after a good pressure washing of the whole truck including all of the suspension and frame etc.