Jorb: The difference in length from "Tube" to "open" is all in the tail housing and the yoke. The yoke went from a trunnion to modern needle bearings. And the modern yoke is much shorter. The late rear casting has a seal and big diameter hole to accommodate the "open" style yoke. The casting is much shorter so the drive shaft is longer than the shaft in the torque tube.The out put shaft is the same. The case is the same. The output yoke changes and the rear housing. That is about it. Inside the case is as has been posted. Lots of changes over the years. Shaft splines, and length however stayed the same.
