would there be any reason why the thrust spring would be missing from my ball diff? i purchased the ball diff used for $15 out of a part out sell.... i threw it in my car and it has been fine. tonight i decided to take it apart and look at it, and when rebuilding i was following the instructions from the online manual and it was saying to install the spring i do not have. other than replacing it is there anything i should do or a reason for it missing? i have raced it three times and like i said it has done fine.