If you still have the factory shifter in place and there is a lot of slop in the shifter ,the springs in the load cups at the bottom of the shifter arm are probably broken or the cups and springs are probably missing .They are available at any parts vendor and will make your shifter good as new .Don't use the rubber replacement though ,use the metal cup and spring as the factory did and grease them well .You can access them by removing the shifter boot and you will see two bolts at the base of the shifter arm ,don't loose the bolts they are special bolts .There is also two rubber bushings the bolts pass through in the shifter arm ,replace them also .