An exemplary product line system includes a common platform and a plurality of component families, each of which includes a plurality of interchangeable component species configured for use with the common platform. The common platform includes an inside drive assembly and a chassis assembly including a chassis and an outside drive assembly. A lockset assembled from the system includes the common platform and a plurality of modular components. Each of the modular components corresponds to a respective one of the component families, and is provided as a selected species of the corresponding component family. The lockset has a function defined by the set of component species installed to the lockset. The function of the lockset can be changed by altering the set of component species installed to the lockset without disassembling the chassis assembly.