When the car was new or with a steering gear in good condition and properly adjusted there will be no play when the wheels are in the "straight ahead" position. Often the steering gear can be adjusted. If the adjustment doesn't remove the play the pitman shaft and bushings are worn out. Also the pitman arm its self is in two sections that are bolted together. There are 4 hard rubber busings between the halves and from grease leakage and old age these busings are bad.
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Chevgene