Please note :
that the Mercruiser, MC-1 lower unit and the Alpha One lower unit can be used
with this upper gearcase.
That said the replacement water pumps are not the same for both sterndrive units.
Example: let say you have this upper gearcase showing and your boat is years 1970 to 1983 our GLM Marine water pump
kit is number 12110 how ever if the lower unit was replaced with the newer Alpha One that came out in 1984 up the GLM Marine
water pump kit is number 12120.
The water pump base, gasket and o-ring is not the same. One way to tell the year
of the lower units 1970 to 1983 is by mercruiser vertical drive shaft end has 1/4 pin about 5/8 long and Alpha drive
shaft has no pin on the end.
It is the year 2020 now so your Mercruiser outdrive lower unit may have been change
after all its 40 plus year old. If your still know sure just send us a picture to firstname.lastname@example.org
or call the order desk for the tech service number.