6000 miles to destroy a set of bushing is pretty poor...Aside from the shocks, is it perhaps a binding issue with the suspension design itself that is causing the clunky feeling? (and taking out the bushing so fast) Any metal to metal contact or binding under travel perhaps?

Do you have an old pair of shocks (assuming they use a similar to stock configuration?) that you can just toss on to go for a run for a few miles to eliminate that ?

Are the shocks a bushing mounting or a bearing setup ?