1998 Toyota Camry can't stop shaking

I have a 98 Toyota Camry V6 that has a vibration at highway speeds. I had the front end aligned because the front tires were worn on the inside edge (not rotated properly), and was told that it was already within specs. I bought 4 new tires and it still vibrates after I took them back and had them rebalanced. I am thinking possibly the CV axles need to be replaced but I hate to throw money at that if that is not the problem. I do not hear any clicking while turning but have noticed that there is "play" in the drive train when going between coasting and accelerating while on the highway. I'm sure the struts could use replacing but I don't think that any are completely shot. I haven't noticed any play in the steering either. Also, I had a four wheel brake job recently and stopping is smooth. Any advise would be appreciated.