chatter from right rear strut

i have this annoying chatter coming from my right rear strut. everytime i hit a bump or pot hole my strut chatters. i thought  it was look and that wasn't the problem. could it be something other than my strut? i am lost

same problem after i put on my eibachs. theres are a few threads on other forums im on and its still a mystery. My guess is the spring isolator pads (the rubber foam pads on the top and bottom of the spring). they dont really sell them anywhere but i heard you can call ground control and tell them you have one of their kits and they will send them to you free + $5 shipping....