i had the exact same problem mate. mine would clunk when braking for speed bumps, turning into my driveway, when braking heavily etc. i fixed the problem by using a breaker bar to tighten my sway bar 'D' bush mounts and crossmember bolts. the problem was fixed!
i had tried installing newer bushes for the swaybar link bits and new rose jointed castor rods also but they didnt help.