As you know, the safe answer, and the right answer is to tear it apart and double check everything according to the service manual.
Depending on what the rear is worth to you, how long you need it to last, and what you expect it to do, you could just tighten it and give it a try.... but there may be more to the problem than that, best thing to do is plan on a rebuild now, the you know what you have when you are really counting on it not to fail.
Grigg
