In 1960 there is a before and after number for the converter and input shaft. Just include the converter if swapping between the early and late. The 904's are all the same length. If you have something longer, it's either a 727 or Powerflite.
I will defer to you on the converter, as I don't have first hand knowledge of the 1960. As for the long tailshaft trans, it is a 904. Maybe a truck? There was never a cable shift 727 for the slant six.
