I was wondering why I was getting low fluid and found out the left rear is a leaker. How do you know whether it's time to replace vs just to rebuild?

Also what tools do you need to do the rebuild? I was surprised to see the Mercedes star on it, that must mean it is original right?

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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.