727 Difference inside

There are three different spline angles in the 727 front planetary.

The spline included angles are as follows:

'62-'75= 90°

'76-'93= 75°

'94-on= 60°

The spline angles are sometimes expressed as the pressure angle which is half the included angle (45°, 37.5°, 30°)

Each change affected the diameter of the splines so smaller shafts will fit in larger planetaries but the loose fit will lead to early failure.


Copied form an old Moparts post (John Kunkel)... just make sure you keep the proper vintage shaft with the proper vintage planetaries and you'll be fine. I would advise you pick up the two common 727 rebuild books available.... look up authors Tom Hand and Carl Monroe. Their books should be read and understood before attempting to swap parts, IMO.