BBforks, thanks for replying. I read the posts about the komatsu seal failure and the field repair that was applied. My guess is that tranny pressure will continue to push tranny fluid into the differential. This being the case, tranny fluid will eventually spill out of the diff vent. So like the komatsu I would have to run some kind of relief hose back to the tranny. I don't know if I can bring myself to do something like that. My customer doesn't mind paying for labor and I don't really mind doing the job. I just have to try and figure out how much of the tranny I have to take apart to get to that seal. I actually have a breakdown of the drive train and I still cant figure out what has to come apart. Break down does not show pinion side of the tranny. Just a breakdown of assemblies. Pinion shaft has a nut on it so I am guessing I can only get to that nut from inside the tranny.