What do you mean by 1/4" of play? If the engine is in neutral and you can turn the front of the driveshaft back and forth 1/4", the play could be in the driveshaft or in the rear axle. If it’s that much play between the front and back of the driveshaft, I’d be surprised that it’s still in the car and not on the roadway. But that much play through the entire rear axle doesn’t sound as bad. Can you hear a gear growling coming from the rear when you accelerate or decelerate but not while coasting? If so, you might want to have the rear axle checked.