Speedometer cable

Oreilly said they do not even show a cable is available in their catalog. Advanced, and autozone said the same thing. Pep boys was the only place that even showed a cable was available. The weird thing is that the speedometer cable was not replaced when it was swapped from a 904 to a 727, so I would expect a correct replacement cable for a 1970 duster should fit. If anybody knows what year the size changed, then that would help a lot.