Tim, Problems with the fine focusing gears stripping on the RZ ProII are somewhat common.
Buying another ProII body, in hopes of being able to cannibalize those exact same gears, may prove a waste of your time and money.
In many cases, the ProII bodies that are sold "as-is," are discounted mainly because of gear problems.
Fine focusing problems have become the Achilles Heel of the RZ ProII.
Depending on your abilities, one might try to convert/adapt a good set of focusing gears and shaft from a standard RZ, and just eliminate the fine focus knob, gears, and it's problems.
I don't know the compatibility of this idea, but it might be worth a go.
Trashed Pro bodies are cheaper, (and more plentiful) then ProII bodies.