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OK, well the 10hp gearcases from 55-57 will interchange, but 58 and later 10hp models used the infamous smaller gearcase.
18-25hp gearcases will fit from 1955 thru the middle 70s will fit as well.
But, it is important to note that the complete assemblies will fit, but there are many minute changes made to the units through the years, so the innards are not necessarily interchangeable. So, do your best to determine the year of the gearcase you acquire for your engine to ensure you find proper parts in the future.
I know it is tough, but do your best to ensure the clutch dog is in good shape on any unit you might buy/acquire. OEM replacement parts for clutch dog issues are a very expensive “kit”.