pitman arm could be worn...mine was so bad it allowed about 1/4 turn in the wheel on top of the normal play. It took me f o r e v e r to get mine off. it has rusted to the shaft somehow. If this is the case, you will want to get a good hacksaw blade set and a torch to heat it. that, and lots of pb blaster.
now, if the play is between the steering box and shaft, then you've got problems, if the input and output shaft turn at the same time w/o play there then it could be the pitman arm, idler arm or inner/outer tie rod ends in that order.
when you say you can grab and turn the shaft, when you do that, what else is turning with that shaft?