[SAJ]

Dave, the first test I would do is sit someone in the parked car driver's seat and have them swing the steering wheel right and left continuously, past any slack in the steering box and far enough to load up all the steering joints, both pushing and pulling on them alternately. While this is happening look under the car at every joint and see if there is any lost motion -any slack that is.
Look at the Pitman arm to steering box connection, at every spring-loaded ball joint at the ends of the track rods and under the car at the big ball joint on the radius rods ("wishbone") under the transmission. This ball will move up and down in the socket if worn.
All this is done with the wheels on the ground and the car stationary.
Then Jack up the car and try to rock each tyre in and out vertically, top and bottom, using both hands, and then do the same thing horizontally. Have someone else look under the car while doing this to check for play in kingpins and/ or wheel bearings. It is hard for one person to rock the wheel and look inside the wheel to see where any slackness is. It is important to visually determine iif the kingpin bushes are slack or the wheel bearings are loose. Both will feel the same to the person rocking the wheel vertically. Horizontal rocking will show up any slack in the tie rod ball joints.
If nothing shows up here then look elsewhere, but this is a very simple starting examination without even getting your hands dirty. Unless your tyres are covered in mud!
SAJ in NZ