Yes, an Oberdorfer pump will physically mount in replacement of a late model Sherwood pump but that does not mean it will provide adequate cooling. In some cases a small modification to the mounting flange may be required. 

The Sherwood will pump more water with more vanes on a larger impeller.

We suggest you follow the engine manufacturer’s recommendation.

Yes. Many M-25, and M-25XP owners report successful replacement. When asked “Have you simulated clawing off a lee shore by running at full  throttle in heavy winds for an hour to test for overheating?” the answer is always “No”.

Yes, but a few customers report the engine begins to overheat when pushed closer to the boat’s hull speed and will continue to get hotter with a longer run. Returning to the Sherwood pump resolves the overheating.

Yes, we include both when you purchase the kit from Catalina Direct.

See the Tech Support articles below “Identifying the raw water pump on Universal engines” and “Raw Water Pump Replacement for 5411, 5424, & M-30 Engines”

If you replace a Sherwood with 1/2” ports with an Oberdorfer with 1/2” ports, the ports are closer together on an Oberdorfer. You must replace the large 1/2” inlet elbow with one offered below under “May we also suggest” #Z3955 to avoid having them interrfere with each other.

You should always have a spare Impeller, Impeller Snap Ring, as well as a pair of Water Pump Snap Ring Pliers.  For Sherwood pumps, add the special Water Pump Wrench too. They are all offered below under "may we also suggest".