After realizing that the prop nut cover on the R29 is a falling off problem - I found that Seattle Marine stocks the brass nut and zinc as one contiguous unit - but I'm not sure that the nut-zinc combination (that Sea Marine carries) will fit on the threads on our shaft. If so it would be a great fix!
Another idea - is there enough exposed shaft forward of the propeller to accommodate a shaft zinc? If there is I will definitely install one the next time the boat is on the trailer.
If none of these ideas work I will have Fishing vessel owners Marine Ways fabricate a nut zinc combination which will solve the problem, it may require a tapered stainless roll pin.
Let me know if you think that the shaft zinc will work.