On MBs it is the lower ball joint that is loaded. You need to unload the joint by jacking one side up and placing a jack stand at the outermost point of the lower control arm. Remove the tire and stick a long pry bar between#6 and #9 the lower control arm and lower ball joint. If you get more than a couple of millimeters, the joint is fairly worn. You can prang around on #4 the bushings for the upper control arm and see if you get any movement there.
I think your clunk may be coming from a broken engine mount. I've seen it before. The weight of the engine shifts once in one direction until you turn in the opposite direction which makes it shift again.
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