A power end includes a monolithic core with a base having a surface configured to mount to a fluid end of the reciprocating pump and a plurality of extensions integral to the base. Each extension of the plurality of extensions includes a ring portion that defines an opening configured to receive a crankshaft of the reciprocating pump. The power end also includes a plurality of plates separate from the monolithic core. Each plate of the plurality of plates extends between a pair of adjacent of extensions of the plurality of extensions to enclose the monolithic core.