OEM Ford serpentine water pump pulley 1989 Ford F250 5.8l. 

There are two versions of this pulley in production that interchange. F4TE-8A528-AA is the later one, production 94-97.  The other is e9ta-8a528-aa, production 1987-1993. 

The e9ta-8a528-aa is a superior part due to the fact that it weighs an ounce more. This is because it is made with more metal in the form of flange thickness.