Just for your information. None of the manuals refer to the hole. Has nothing to do with gaskets or O-rings. Finally found a mechanic locally that is familiar with the problem. That is a manufacture hole that had a bearing plug that evidently blew out. Doesn't go anywhere. Doesn't provide fluid to anything. It's dead end. John Deere can't help, no info. Nobody knows why it's there.
Tapped the hole with 10-24NC tap & placed a 1" machine bolt covered in Locktite. Works like a charm. NOW YOU KNOW the rest of the story.
Thanks for all your help.