I just went and checked, mine measures 23" in a factory 318 Duster. 26 radiator fit right in though, ~1" per side is blocked, but I wouldn't consider it useless, still a larger fluid capacity in the radiator.
I ordered a Cold Case radiator. Should be a direct fit and bolt up to my factory holes. The setup I'm going to use should work pretty good. I'll be getting it in today so we'll see how it goes.