Volvo Penta 2 groove pulley part #833002.  I believe this part number is an old one and that this is a discontinued part.  I believe the application is for the earlier small Volvo Penta sailboat diesels (MD2B, MD11, MD17, etc.).  Bolts to front of the crankshaft to run alternator belt and an additional groove for running an add-on water pump, etc.  Pulley is new, never mounted, but does show some shelf wear.  See measurements in pictures.  Contact me for additional measurements if needed.