As I understand it, installing a double-DIN just requires cutting the hole a bit larger in the dash and maybe putting in some sort of trim. The factory hole is a bit smaller than double-DIN, but there's nothing too hard about enlarging it. (I have not done this myself, though.)
I'd look for the E series under "Econoline" for 2005...though realistically, any double-DIN radio should fit after dash modification. If you're looking for door speakers, having the right vehicle selected may be more important.
