Small block Chevy, single groove, short water pump pulley. 7.1" diameter, 1.75" bolt circle. Chrome steel. Also available in part #S9600X style.

DON'T KNOW WHICH YOU HAVE? IF YOUR ALTERNATOR IS ON THE DRIVER'S SIDE OF THE ENGINE THEN IT'S A SHORT WATERPUMP, OTHERWISE IT IS A LONG WATERPUMP. ALSO, IF YOU CAN FIT YOUR HAND IN BETWEEN THE WATER PUMP AND TIMING COVER THEN YOU HAVE A LONG WATER PUMP.