A round baler having a frame assembly, comprising: (a) a first frame assembly; (b) a pickup assembly comprising a pickup and a auger assembly integrally mounted on the first frame assembly to form a pickup module; (c) a second frame assembly connected to the first frame assembly; and (d) a conveyor module selected from the group consisting of a stuffer module and a rotor module, wherein each conveyor module comprises a conveyor mounted on the second frame assembly. The modular structure of the frame assembly facilitates manufacture of several diverse types of product balers while minimizing the complexity of the assembly line process.