In park with the wheels on the ground, it probably won't move at all.
What you want to do is put the trans in neutral and set the E-brake.
Put one hand on the U-joint, rotate the shaft, repeat on the second joint. There should be no play in the joint.
Grab each U-joint in turn and push/pull in back and forth. there should be little to no side to side play in either yoke. Spinning the driveshaft back and forth by hand, you may have as much as 1/8 turn of play without having any internal problems.