You've got it backwards. The manual hubs chew up the end of the axle when the c-clip pops out. The auto hubs just break.

There is no spacer. There are some shims, but the only thing holding the axle into the manual hubs is a 26mm snap ring over the splined diameter of the axle. I would hedege the bet the axles you pulled were damaged to start with. When they grind for a while, it is not very ovbious as the wear is very smooth and the resulting metal dust looks like grease.

Good Luck,
Michael