90 240sx Diff axels???

[trigger94587]

Ok heres the problem, my car clunks when im going to bumps and rocky bumpy roads but not on a straight roads. So I put some sub frame collars on it but it dosent help. then I rise my car and move everything below my rear sub frame. and when I try to move this (shown on the picture) I can hear like clunking and its moving. Do u think its normal? or its the one causing the clunk sound? How can I fixed it? Thanks!