Tropical Zed

Hi all. I've just joined this forum. I live in Clifton Beach just north of Cairns QLD. Have a 1972 240Z. Could you guys put me onto suppliers of parts for Zeds in Australia. I may be in new of a replacement differential. I have just had the front diff insulator mount replaced and now whenever I move off with the car and change gears there is a loud clunk coming from the back of the car. I didnt have the noise before I had the new diff insulator mount installed. I am concerned that I have too much backlash as with the car stationary, I can crawl under the car and twist the drive shaft and I am hearing a loud clunking noise which seems to be coming from the ring and pinion in the diff......but I am not 100% sure. There used to be a ZCar workshop in Brisbane, but Alan, the guy who owned it, retired. Any advice would be appreciated. Cheers