I recently swapped the lower unit on my 1966 9.8 with the lower unit from a 1973. It was a straight up swap except for the shift rod and prop shaft. My old prop shaft had 5 splines and the newer one had 8 splines. Did mercury use this same configuration of prop shaft with 8 splines through the 1979 models? I've got a chance to pick up a complete prop shaft from a 1979 and thought it would make a good spare.<br />Thanks, Walt
