The electric motors for many of the aftermarket waterpumps appear to be interchangable. Although the picture I included below shows a CSR brand motor that’s being borrowed from my FE Ford electric pump and being used on a fabricated Y waterpump housing, the EMC engine actually used the motor drive from a ProForm electric water pump for a small block scrub. These two were totally interchangable.
Lorena, Texas (South of Waco)