Only reason I thought that is my father in law works at a power plant. They have a steam turbine driving a big generator. I don't know the specs but its pretty big too.
Reviving my original post. Looking at the gearcase housing from a 1971 OMC 9.5, they look the same. Does anyone know if they will interchange with a 1958 sportwin 10? If I can't find a good used gearcase with a good driveshaft bushing I am going to have a bronze sleeve installed in one of the old housings I have. Its still running and pushing the boat fine, even with the damaged pinion it planes out my light 14 foot jon boat and gets me up to 15 mph with a load of fishing gear and my 315 pound self lol. I just know its a matter of time before the lower unit goes boom.
The housings ar indeed the same. Gears are not. The 9.5 uses splined pinion, the 58 uses keyed. Your motor will use the same 10hp unit, as an assembly, up to 1963. Those guts, as a set, will work in the later 9.5 housing.