sounds like your tranny is going bad but 4th is usually the 1st to go on gtps
the hub is about 131.99 - 127.99 for the good ones where i live, they arn't that hard givin you have the right tools just make sure you don't rush and do the job right
hub reinstall: http://www.grandprixforums.net/f73/h...ubs-10985.html