Your best bet is the latest model 7.3L PSD Ford you can find in that vintage/price range.
2003 is the last year of the 7.3L PSD. Many 2003s actually have 6.0s and you will have to verify the engine.
2001-02 Duramax's had some fuel injector issues, which is an expensive issue, but the engines and transmissions are solid otherwise.
ALL of the Dodge automatic transmissions SUCK of that vintage, but if you can find a rebuilt or upgraded tranny truck, that's a good deal too. The 12 and 24 valve Cummins are strong.