knock knock?

[macspratt]

Hi guys,, ive just started to notice a slight knocking noise coming from rear,,,first thought was new back box ive fitted or breaks,ive now ruled these out.
The problem isent there all the time,seems to be back right side going over rough ground,and more apparent when turning left.
Hard to describe the sound more like the back box is knocking under the wheele well,but there is loads of play there.
I this the dreaded droplinks?,if so how easy are they to replace,any links?

Aidan,PASSION RED GR, V-R SPOILER, ITG, 17S POWERFLOW 5"