Sounds like the rack dampener needs adjustment. It is located on the back of the injection pump. Warm up the engine and then loosen the lock nut and screw in the adjusting screw until the shacking stops. You may need a new one if this does not help.

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Mark
82 300SD 110k
91 Caprice SS
92 Jetta TD
97 Cadillac Concours(300hp)
84 Celebrity 4.3L diesel