OK I sold my GS...this is happening with my brothers TSi AWD now..

on the top part of the strut assembly, the nut that holds everything together is on, but when I lower the car onto the ground its higher than the left. a lot higher. and when I test drove it down the block, theres a knocking sound coming from the rear right. I stop, pop the trunk, and I wiggle the washer that the nut is on, and its loose. the other side is fine, just the rear passenger is being weird. any thoughts? it seems this problem has a thing for following me around. did I assemble anything wrong? any ideas at all? Ive been on this now for 2 days, and its aggravating me.