I have the equipment to pull the engine and I would pull both the engine and trans as a unit because in the long run, it is easier. Most people wouldn't pull the engine to do a timing chain but after seeing a lot of problems in the front of these engines, I would pull the engine and replace ALL the guides including the oil pump chain and its tensioner. But, that is just me. I have a tendency to over repair my own cars. I look at it as "do it once, and do it right."
Paul

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84 500 SEL (307,xxx miles)