73 duster radiator

Unfortunately no fender tag it wouldn't be a 26" radiator as the mounting bolt holes are 25 1/2 center to center

That's just strange. Do you have any pictures of the whole radiator support showing the mounting points?

The stock mounts on my '74 Duster are 24-1/8" center to center, it had a 22" originally. The mounts for the 26" radiator in it now are 28" apart, and they were located from an OE 26" radiator from a '74 Dart.