It all depends on how it was taken care of and how it was driven....but if you check it out thoroughly and it runs okay, its "probably" okay.....

I have a buddy that had one as his work truck with the 5.4...he beat the living shit out of it, never changed the oil, didn't take care of it and it took a shit at like 75k miles. So, just check it out thorougly - see if the owner has service records on it or anything.