A vehicular transmission embodying the concepts of the present invention permits facile construction by virtue of a modular construction. Such a transmission has an open ended central housing module (12). The annular stator (26,32) of one motor/generator (24,30) is supported interiorly of the annular central housing module (12), in such a manner as to circumscribe the longitudinal axis of the annular central housing module. A rotor is operatively positioned interiorly of the stator. The modular transmission incorporates a modular input closure subassembly (20) and/or a modular output closure modular subassembly (22). A closure subassembly has an end cap and a retaining shroud demountably attached to the end cap, and the closure subassembly is demountably secured to an open end of the central housing module. An input shaft member (66) is coaxially and rotatably supported by the input closure subassembly (20), if employed, and an output shaft member (158) is coaxially and rotatably supported by the output closure subassembly (22), if employed. One or more planetary gear subsets is coaxially supported in selected closure subassemblies to circumscribe the shaft member associated with the corresponding closure subassembly. A torque transfer device may be provided to selectively connect the planetary gear subsets and motor/generators to selected shaft members and selected shaft members to each other.