For the last 4 years we have been pushed along by a 1993 2 cycle 9.9 Mercury on our 1983 25. This year we had a problem with reliability (since solved) and not knowing how reliable the old engine would be, we chose to buy a new engine. We chose a 6 HP Tohatsu, hoping it would prove adequate. Its an extra long shaft (25") manual start with a slightly lower pitch 8" prop. This is standard on the extra long shaft. To our surprise, the 6 HP proved as capable as the old 9.9 and under some circumstances better. The very long shaft stays under when the boat pitches in a heavy chop. We can get up to 5 knots without a problem. The single cylinder is not as smooth. Also a bit noisier. Gas mileage is about double the old 2 cycle. We now have a 3 gallon tank where we needed a 6 gal previously We miss the electric start though. Just posting this in case some of you need new outboard power.