OK, I guess I stand corrected. Not knowing anything about circle track racing, I guess maybe it was used for that purpose. The ring gear itself was like new, no chips or unusual wear. I just was hoping to hear from someone that it really is a locker. The fellow that sold it to me advised that he had already had it opened and that it was in excellent shape. He said he bought it for a project car (as I just did), and unfortunately never did install it. I just wanted to be sure that I got what I paid for, a true Detroit Locker.