The 2004. 5 will say 325 on the "Advertised hp" on the white sticker on the driver's side of the valve cover. the 2004 is 305. Also, the watsegate on the turbo on the 2004. 5 has a wire attached to it (electronic), and the 2004 does not.
my 2004 has the catalytic converter but it had the sticker saying 305 then after a program up date now the sticker is gone and was told after the update was done now is 325. as my build date was the last week of the 305 and my truck was on the last day before they switched over to the 325