18 Spine Aluminum Case A-833 4 Speed Questions

I'm not super familiar with all the 833 tranny's but it does seem to be that someone could have upgraded this trans with the 18 spline shaft. IMO, it was not needed. The 23 spline can hold a lot of power. If your deadaceded drag racing a car, that would be a different story. (And not a meek double digit 1/4 mile runner either,)

As far as I know, the aluminum case was part of the feather duster package.