In assembly manufacturing systems there are points in the production process where several component parts are put together in areas called assembly cells so as to form more complex parts called subassemblies. In this paper, we present and compare two variants of the Extended Kanban Control System (EKCS) - a recently developed pull production control mechanism that combines base stock and kanban control - for the production coordination of assembly manufacturing systems. In both variants, the production of a new subassembly is authorized only when an assembly kanban is available. Assembly kanbans become available when finished subassemblies are consumed. If an assembly kanban is available, in the first variant, each component part of a subassembly is released into the assembly cell as soon asitis available (independent release). In the second variant, however, it is released only whenallother component parts also become available (simultaneous release). In both variants, when a component part is released into the assembly cell, it releases its kanban, thus authorizing the production of a new component part.