Shaking from passenger side rear?

Anyone have an issue of shaking from right rear a bit... more so noticeable by seeing the passenger seat shaking/vibrating. Thought back right tire needed balancing, had it balanced, seemed to be better for a week or so and seems to be doing it still... thoughts?

 

Worn out shock?

 

same here passanger seat vibrates side to side
2000 prerunner v6

 

I believe it stems from the natural in cabin harmonics presented through the frame and suspension during drives.

Edit: Mine does it. So it is no a 1st gen exclusive issue. If it is excessive shaking then you may have a cause for concern, if not, you are fine.

 

check your tires for tread separation...Our stock tires caused all kinds of problems...the tread looked bubbled out.

 

Just a thought but check for breaks in your leaf springs