rear leaf problem

ok so i installed my rustys 4.5 lift came with full leaf packs. at the back where it bolts the the stock shackle when it compresses the shackle will smack the body behind it. this picture i found shows what im talking about..the shackle will compress and hit the metal behind it making a loud thud everytime. what do i do to fix this?

Boomerang shackles or relocation brackets.

I cut a notch out of the back panel on mine for that reason.