Here is some pictures of the different diff's for the auto drives.
Why they changed I have no idea,could be a better design or a different supplier I don't know.However the the later model one was the same as the power-plus had.
Mark I,II & III
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Mark IV only
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Mark I,II & III
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Mark IV only
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Just a few things to show you all that they are the correct blade discs.As well as the part numbers to match.
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Here for a good time,not a long time.