Hi all , im posting now to explain ive finally fixed the ' so called diff clunk ' ! , (which had zero to do with the diff or bushes ). What a frustrating journey! ,after mAny posts on this same topic asking for help ,and taking the caR TO 2 reputable performance garages and a Ford Dealer , and everyone throwing in their two cents to help , it turns out the annoying THUMP under the car ,which occured when the auto shifted down a couple of gears , is the result of a previous owner meddling with the Auto. The valve body and solonoids were replaced and now the Thump is gone . Andrew at Preston Autos and differentials in Preston resolved the issue and fixed it. If anyone in Melbourne needs work done on their auto or diff, I would highly recommend Andrew. He is honest, professional and charges much less than other places . He also built the BA Clinic cars auto that did under 9 secs at the 1/4 mile also. I was at the point of selling the car because the THUMP annoyed me that much , and thanks to him I dont have to, such a pleasure to drive now :-)