[Formulalt1]

It will rise toward the floorpan as you remove the connection to the tranny but there isn't a ton of pressure on it and like stated with the control arms in place and the rest of the rear suspension it will roll just fine.

Edit- Also you are correct you need the tires off the ground to get it to move back in place or else you are trying to move the car's weight (forward or rear motion)by the arm.