Chatter noise from rear while driving

[3.0Ranger]

When I'm driving my 1998 ford ranger 4x4 3.0 5-speed i can hear a chatter noise coming from the rear of the truck when I go over a bump or the road gets rough. But when Its parked I looked underneath all seems to be tight. Any Ideas? Could be back brakes?

 

[Defective]

I'd be checking for broken leaf spring.