I had to change a rotor on my F250 yesterday. I noticed a lot of the videos I watched showed a snap ring on the groove that is furthest back on the passenger side of the axle. However, mine was on the groove furthest to the outside end of the axle.

Is there a reason for two grooves?

I saw diagrams showing it in either one place or the other as well as a snap ring on both grooves.

What does this snap ring actually do?

 

Front axle right?
I am guessing the ring goes on after a spline adaptor for the 4x4 hub goes on?
It would keep the adaptor & axle from moving away from each other.
Also would hold the axle out so it keeps the axle joint in line of the ball joint pivots other wise you would get binding.
Dave ----

 

Don't the D50 and D60 share parts from the knuckle out?
Second (outer) groove might be so the D50 doesn't push the shaft through the lockout as the TTB flexes on its springs.

You wouldn't have any of that with a solid D60.