Heres are video of my rear end problem in my 93 v6 4x4. The ring gear is in good condition but you get a good amount of play out of the rear end when your driving. Check out the video?
Also something I never really thought of, when I spin the shaft on the diff it turns both axles does that mean I have a locker? I've only had this truck about a month and don't know much about it.

http://www.youtube.com/watch?v=3xBzNQZ5LaI

 

That's normal slop if you have a lockrite in there....you have a LR if both axle shafts turn in the same direction when you spin the pinion. It's a factory "open" diff if they rotate in opposite directions.

 

I really don't know much about these toyota's but from my working with chevy differentials I would say that is normal.

 

Sometimes the slip yoke in the drive shaft can feel like play in the rear end when it is not lubed properly or the rear of the vehicle has been lifted and its at a funny angle in relation to the rear end.