The water circulating pump on the closed cooling system is leaking out of one of the weep holes the mercury # is 811573A04 at $325 bucks. Will the Sierra #18-3577 work ? or does anyone know which one will ?

An old Thread,but exact what i also like to know!
There are some aftermarket pumps with referenz number 811573 in description!
Will they fit for Merc number 811573A04???
Michael