Vibration 45-50

So just got back from a drive/ Car has not been started until now. When cold there is no vibration, after engine reaches op temp and after shifting up and down a number of times, the vibration starts to show itself. I think it's in the 833. As soon as I put in N, vibration gone. Not sure what is spinning or stops spinning in the transmission. I have been searching for a unit that is in working condition to swap with this one. Haven't found yet. Passon has units for sale. Brewers does not.