Check the ball joints two ways--with the suspension hanging--- 1. pry between the control arm and the bottom of the strut to see if you can detect movement. 2. Squeeze (with a giant size "water pump" type slip joint pliers) between the bottom of the strut (wherever you can get a grip) and the bottom of the control arm to see if you can create movement. There should be NONE with either check. That all being said--I did once check an 850 that way when changing control arm bushings and found the ball joints loose when separated from the strut. In that case I elected to purchase complete control arms as a better solution. If the ball joints are a bolt in deal on the XC70 the worst that can happen is you'll need to replace them. You'll know for sure when you have it apart. -- Dave