what is the best think to use when polishing parts such as water pump housing, alternator bracket, the outside of the throttle body. stuff like that. thanks

 

start with a rougher sand paper on a orbital sander work your way to super fine, not sure of the grits off of the top of my head, then use something like never dull when your done sanding. im sure there are better ways but that is the only one right now that is relativly easy

 

Wire cup brush or wheel

 

dont forget the never dull!!!

 

Best?
Industrial polisher, followed by a wheel with polishing compound on it, and finish with a nice anodize.