Clickety, Clickety, Clickety Rear Axles

I know a grinding noise is a symptom of a problem. The 8 3/4 differential swapped into our '65 Formula S turned out to need a rear axle bearing replacement after hearing such a sound.

But the clickety, clickety I now hear after pulling the brake drums and turning the axles by hand (this is from a 1974 Dodge Dart 7 1/4 differential) has me wondering. I hear it on both driver's side and passenger side. I guess I could say I not only hear it, but I can feel it somewhat by way of my fingers as I slowly rotate the axle(s).

Is this a problem or just normal noise? Thank you.