Popular short style water pump that was originally used on pre-1969 small block Chevrolets. Pumps are built using all new components and an aluminum body for added weight savings over original cast iron pumps. Pump features a 3/4' main shaft and bearings with a 5/8' pilot and a billet steel hub drilled for both small and large fan bolt patterns making this a good choice for street and mild performance vehicles. Block mount to fan hub dimension is 5-5/8'. This pump is not recommended for use with mechanical fans over 5,000 RPM. Above this RPM, use the ALL31105 pump with a 3/4' shaft/bearing. Water pump may need to be clearanced for use with 8' dampers.