[JCD]

It's not always the ball joints or the rag joint..

The one part of the steering wheel play that few address, is the play in the steering box itself.
On the top of the gear box there's a locking nut that holds the adjustment screw in place.
Back off the nut, and turn the adjustment screw clockwise 1/8th turn to start.
If that doesn't do it, try another 1/8 turn.
I've done this in the past to several cars, and it improves the steering immeasurably.

J.