My F250 has 140,000 kms on it, 2005 model, the left ball joints were done by the seller after a pre-puchase check. One year later I had to do the right hand side. No biggie.

The other thing I found as per Adrian's post above, the front leaf springs had sagged about 1.5" in the first 6 years of life, due to the enoumous weight of the 7.3 sitting over the top of them I expect.

The steering and handling were not very good, I just put it down to it being an F250. I ended up buying a +2.5 " add-a-leaf kit from the US which came with spring packs, drop radius rod mount etc. You just add the leaf packs onto the stock 2 leaf suspension. What I got was a complete transformation: +4" over the sagged height, better ride, better steering - all because of the improved suspension travel.
Again, not a biggie, fairly cheap and easy to do.

The indicator to look for to determine if the truck has sagged front suspension is look at the front sway bar ends. If they are pointing down towards the road the front end is sagged.

The truck might check out really well but have a few rattles in the front end and ride choppy because of the limited suspension travel of a sagged front end - but don't consign it to the waste bucket because of these issues. They are the cheap easy fixes.