it is hard to tell with out seeing both pullies here is the stock pully and what u can look for
in the first pic the stock pully is about 2 3/4" wide.
in the second pic the washer and rivit is centered on the cutout.
the thickness is about 1/4"
this needs to be measured with a caliber to be 100% what pully it is.

look in the pic above you will see how the rivit is not in the center of the code 3 but is in the stock ones. jim