If you have transmission fluid leaking out of the side of the trans at the selector shaft, this is the culprit.
You remove the shift lever with the ball attached. You will find it easier to remove the shaft than to try to replace the seal with the shaft in the trans. To pop the shaft out, you put the transmission in neutral, remove the small housing that holds the reverse light switch and the shaft will slide out. Replace seal slide shaft back in and put a light coat of sealant on the reverse light switch housing and you are good to go. Reinstall lever.