Pop your shift boot off so you can get to the bottom of the shifter. A metal rod fits into the top part of the shifter. The part you see and the part that the knob screws onto. The two parts are held together with rubber and it wears out. Hold the bottom piece and move the top if you feel a lot of play your problem is the non replaceable bushing is worn.
You can remove the shifter and drill out the rubber and replace it with epoxy or windshield urethane. Epoxy is more like a welded shifter, they transfer more gear noise.