This is currently my only MSM piece, but I would love to change that
I bought this off John Loughner (SteamerJ), you might recognize the name from his work with Jensen
I will have to look at his old posts and see if he says anything about the pulley...
I've bought a LOT of engines and bits and pieces from John (very nice guy), if you bought it from him I'm leaning towards it being a PMR pulley.