Tim,
I work in an Auto Value parts store. Just about any of them can get a radiator for you. If necessary, take the measurements of the core and make sure you know where the fill neck, lower port, and tranny lines exit. Don't try an Autozone or Advance, but a good old neighborhood parts store should be able to get you one. If you need an aluminum one, find a Griffin radiator rep near you and they may still be able to get one for you. You would have to have someone weld brackets to it for you though.
Ralph in MN