I replaced my lower seal after 246,000 miles, then i just replaced it again after 118,000 miles, so yes it may leak again, but it may not be for a LONG time. And yes I have 365,000 miles on my steering box, and also on my power steering pump, and on the engine come to think of it...
So you have a chance of fixing the leak for a long time, or of having it leak again right away, but for an 18 dollar seal I tend to take that chance, although I will say it is quite a bitch to replace that seal. It took me about 3 hours and this is my second time doing it and I have all the tools needed for it. Oh and it makes a big mess to replace because if it is already leaking out of the bottom, think of what happens when you start loosening things and messing around with all the parts down there, it just comes out faster and faster.
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