Do you have to pack the bearings with grease?

about to go to plugs and wires, and my father just asked me if I packed the bearings the other night. I was told to just grease the spline. Do I need to pull it apart? If so, what part needs to be packed with grease? Please repy ASAP, I'm waiting to go back outside to see which job Im doing.

The ones he's talking about are the old style where you just change the bearings and not the whole hub assembly. The sealed units are pregreased, just Plug N Play.