Rolling "on and off" the throttle in top gear producing an unsettling noise.
Sure, you're experiencing all the total play in the complete drive line, starting with the clutch all the way to the dampers in the rear wheel.
As the miles accumulate, so does the wear resulting in lots of play (relatively speaking) which will be most pronounced in top gear at moderate speed.
I would suggest to not keep "testing" the play since to do so will tend to aggravate the situation and can make things worse.
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and?