I'd say you might be able to take the entire DS out and have the it checked and balanced and see if it goes away. Flex discs are there to take up some of the shock, AFAIK. When my flex disc had a crack in it, going from neutral to reverse was jerky.

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
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