A method of modification of a railcar which includes providing an existing railcar with a cold formed center sill; removing an upper portion of the railcar; Cutting and splicing the center sill; Forming an upper railcar body having top chord sections and a pair of end walls and side walls coupled to the top chord structure, wherein each sidewall includes a side sheet, a plurality of side stakes and side sill; Forming an underframe construction including the spliced center sill, bolsters configured to be above truck assemblies and coupled to the center sill and a plurality of lateral I-Beam cross bearers that extend from the center sill toward and stopping short of the inside of the side sheet, and wherein the cross bearers include vertical connection plates configures for coupling to side stakes which are positioned between the bolsters; and Coupling the upper body to the underframe.