Hi Steve,
I just replaced one of the axles on my '80 300D. I didn't use a special tool, just a dowel and a hammer to drive the axle out of the hub. I'm not positive on the 300SD though. It would be my guess that the clunking is just the CV joints. The boots on the passenger side of my car dried out and broke open. Of course all the oil flew out. The joints were so loud it was embarassing. It was so bad that the car shook while driving at highway speed. Any special reason why you want to replace the differential?

Andy B

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burnan
1993 2.5 turbo