Is it power or manual steering? First you want to check the play between the steering column shaft and the input shaft of the steering gear box. You can usually do that under the hood by grabbing the steering column shaft just anywhere and turn it back and forth and watch how much play is in the rag joint until the input shaft of the gear box starts to turn. There should be very little or that rag joint is worn. Next would be the gear box itself, turn the input shaft and watch as the pitman arm starts to move, there should be little movement in the input shaft until the pitman arm starts to move. If looking at the steering wheel I would say no more than 1-2 inches of free play. If more the gear box is worn. It would be easier to test that while the front wheels are off the ground but not necessary. Next, you will have to jack up the front wheels until off the ground. If your arms are long enough to reach across the entire front end and grab both fronts of the tires and pull in and push out on both and look for any play in the tie rods, center link and idler arm. If you cannot reach across just jack 1 wheel off the ground and grab the tire at 3 and 6 o'clock and push in and out while looking under the front for play. An idler arm is allowed maybe 3/8" up and down play, tie rod ends almost none as well as the center link. Next check the wheel bearings by jacking up till wheel off ground, grabbing tire at 12 and 6 o'clock and pushing and pulling in and out, there should be very little play, if more than 1/4" tighten up the wheel bearings a little, but never down to zero play.
Next to check are the ball joints. With coil springs between lower control arm and frame, to unload the spring pressure to check the balljoint, just jack under the lower control arm at the outer most spot until the wheel is off the ground enough to stick a tire iron or big prybar under the tire. To check the lower balljoint place the prybar under the tire and pry up and down on the tire and look around at the space between the spindle or knuckle and the lower control arm while you pry up and down. That should not move more than 1/4 " or the balljoint is worn. to check the upper balljoints grab the tire at 12 and 6 o'clock again and push and pull at the top of tire and watch the balljoint and the spindle or knuckle, it should not move in and out more than 1/4" or that balljoint is bad.
Another way to check tie rods is by squeezing them usually with a big pair of channel lock pliers and they should not move in and out more than 1/8". Or you could use a big prybar and find something to set the prybar on and push in on the tie rods.
As far as the shifter is concerned if there are any bushings at the linkage end on transmission shift levers, make sure they are not worn out or missing. Make sure all the nuts and bolts are tight. If the play is coming from inside the column itself, I would dissemble the column and look for any worn or loose parts, etc.