Abstract: The present invention provides a method of casting a sideframe including the steps of dividing the sideframe into design zones, and providing a core module for forming internal surfaces of the sideframe casting in the design zones. The design zones include a right outer leg design zone, a left outer leg design zone, a right tension member design zone, a left tension member design zone, and a bolster opening design zone. The present invention also includes the step of varying at least one core module to correspond with varying sideframe casting geometry in at least one design zone. The core modules include a right outer leg core module, a left outer leg core module, a right tension member core module, a left tension member core module, a right column wall core module, a left column wall core module, and a bolster opening bottom core module. The core modules define internal surfaces of the sideframe casting in their respective design zones.