What will work

Well there Dusterkid, it looks like your car could've come with either a 19" or 22" radiator in 73, so the first thing I would do is measure the opening and then determine what radiator you need by the size of the opening. A 225 shouldn't need more than a 22" rad, and this would be a good size. The part number for a 1973 Duster with a 22" radiator and slant 6 would be 3673005, and a 19" radiator is part number 3673004. Is this the info you need??? Geof