"Where do you get parts inexpensively and quickly?'
Doubt that happens. You may find one in a salvage yard. but it may not be much better shape than what you started with.
Quickest would probably be through your nearest CNH dealer. Be ready for some sticker shock. All companies seem to be pretty proud of them parts...
You can go to CNH's website, and go to the construction side, then bring up the parts search. Type in your model # and it will display the whole tractor in an exploded view, section by section. The part numbers are listed.. You can copy and paste them in Google search, and if there is one on the net somewhere, it will pop up. Or..., just use the numbers to make sure your on the same page with the parts guy at a dealership.
Good luck..!!