Switching a water pump from a 74 with a crack block to a 69 block. Part numbers look the same, but the pulley wheels are different I think. The outside diameter looks good but when trying to put the pulley wheel on, it barely fit between the mount bolt and pump. Course I tried to stick the old wheel on the new pump.. Found out the hard way the 74s bolt spacing is wider. Outside diameter is the same by eyeball. I know, should go brand new, but I'm trying to solve a different issue the cheap way... Sent from my VS425PP using Lake Ontario United mobile app