An electric motor assembly includes a stator assembly and a rotor assembly having a shaft disposed within a motor case. The motor case includes an endshield with a centrally disposed bearing-receiving core that is configured to receive any one of a plurality of bearing assemblies, including at least a ball bearing and a self-aligning bearing, for rotatably supporting the shaft. The core includes a bearing assembly engagement surface with a generally cylindrical first portion and a generally frustoconical second portion, such that any of the selected bearings received therein directly contacts and engages the first surface portion or the second surface portion.