2002 Pontiac Grand Prix vibration under accel.

My wife's car vibrates pretty significantly under a right-turn acceleration, like on an on-ramp or long curve. It also vibrates a little while accelerating in a straight line, though not as bad, and isn't noticeable at all under left turn accels. I've done a little research on forums and am pretty sure it's the axle assy/cv joint, but is there a way to tell which side is bad? They're fairly cheap and I could replace both, but would rather just replace the bad one. Thanks.