The 7.3 is a half million mile engine, if it is properly cared for. I have owned 14 Fords with the 7.3 Powerstroke engine in them. Ever one I purchased ,had over 225,000 miles on them when I bought them. Many, I later sold to friends, and they are up around 375,000 miles now, with no major engine problems. As long as you stick with the 7.3, anything under probably 350,000 miles is not too many, if you can verify that regular maint. has been done on it. Be aware that the lousy 6.0 came out in 2003 model year.