The jag rear end is susceptable to the outer fulcrum rods wearing, which gives the hub a little play and hence a clunk. Also it can cause a shudder when pulling off and make the car pull one way when accelerating and the other when braking.You need to check all the universals as well which can also cause "clunking".I use a hypoid 90w and a limited slip additive (if you have an LSD" .Sometimes the big center nut on the axle will also come slightly loose (even with the pin) and may require a little shimming to get no play. Don't just tighten these!
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