So I have both a 1966 Evinrude 9.5 and a 1972 9.5. The 1966 runs better but I think the clutch dog is gone as it pops out of gear under a load. Can the 1972 lower unit be swapped in to the 66 model or do I need to consider a rebuild? My other option is to swap out the transom mount into the 1972 and do some powerhead work. I'd appreciate anyone's thoughts on anything else I should consider as well.