The prime place to look for a leak of transmission fluid is the hard lines. Check where the clamps are, as the rubber tends to disentigrate over time and the result is metal-to-metal contact. Vibration will wear the wall of the hard line so thin that it may not be readily visible without removing the clamp and watching the area, while running the engine. New hard lines are available, through a dealer, for ~$50. You can try a band-aid fix of flex line over the hard line, but in my experience it is likely to not last long.

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Sam

84 300SD 350K+ miles ( Blue Belle )