With the trans in park and neutral there isn't much of anything inside the trans that is spinning , the input shaft , the rear clutch retainer and the maybe the front clutch via parasitic drag, which would spin the sun shell, everything that is splined to the output shaft is not moving if the car is not moving .

Anything bolted to the the crankshaft is spinning when the engine is running and it becomes part of the engine imbalance equation.