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The 105 (S/N 218010 - 306085) was built between Nov '67 to Aug '69.
My guess, is that you sheared a pin in the Coupler at the Hydro Input shaft. Check to see if the hydro input shaft revolves when the motor is running.
YES, parts are available. Your local CC or Case/IH Dealer should be able to get you the parts needed. If not, the Sponsors in the boxes at the top of the page, are more than willing to help you out.