A modular shaft assembly for use with a variety of different endoscopic forceps each having a housing including a handle assembly and at least one moveable handle, the modular shaft assembly comprising: a shaft having proximal and distal ends; and an end effector assembly including a pair of jaw members (110; 120) attached to the distal end of the shaft and a universal drive assembly attached at the proximal end of the shaft, wherein: said universal drive assembly is operably engageable with the handle assemblies of the variety of different endoscopic forceps such that actuation of the at least one movable handle of any of the variety of different forceps causes the universal drive assembly to actuate the jaw members of the end effector assembly to move between an open position wherein the jaw members are disposed in spaced relation relative to one another to a closed position for grasping tissue therebetween, said modular shaft assembly being characterized in that the shaft includes a plurality of mechanical interfaces that are configured to mate with a corresponding common plurality of mechanical interfaces disposed within the variety of endoscopic forceps; the plurality of mechanical interfaces that are configured to mate with a corresponding common plurality of mechanical interfaces disposed within the variety of endoscopic forceps are disposed on an outer periphery of the shaft; the shaft includes a bushing disposed on the shaft that mates within a corresponding mechanical interface disposed within a distal end the housing; the shaft includes a rotating assembly affixed atop the shaft for rotating the shaft relative to the handle assembly with which it is engaged; the shaft includes a knife rod disposed in said shaft and a knife actuator that slideably mounts atop a midway portion of the shaft in between the rotating assembly and the bushing; and an elongated slot is defined within the midway portion of the shaft and cooperates with the knife actuator such that said knife actuator is adapted to advance and retract the knife rod. a shaft having proximal and distal ends; and an end effector assembly including a pair of jaw members (110; 120) attached to the distal end of the shaft and a universal drive assembly attached at the proximal end of the shaft, wherein: said universal drive assembly is operably engageable with the handle assemblies of the variety of different endoscopic forceps such that actuation of the at least one movable handle of any of the variety of different forceps causes the universal drive assembly to actuate the jaw members of the end effector assembly to move between an open position wherein the jaw members are disposed in spaced relation relative to one another to a closed position for grasping tissue therebetween, said modular shaft assembly being characterized in that the shaft includes a plurality of mechanical interfaces that are configured to mate with a corresponding common plurality of mechanical interfaces disposed within the variety of endoscopic forceps; the plurality of mechanical interfaces that are configured to mate with a corresponding common plurality of mechanical interfaces disposed within the variety of endoscopic forceps are disposed on an outer periphery of the shaft; the shaft includes a bushing disposed on the shaft that mates within a corresponding mechanical interface disposed within a distal end the housing; the shaft includes a rotating assembly affixed atop the shaft for rotating the shaft relative to the handle assembly with which it is engaged; the shaft includes a knife rod disposed in said shaft and a knife actuator that slideably mounts atop a midway portion of the shaft in between the rotating assembly and the bushing; and an elongated slot is defined within the midway portion of the shaft and cooperates with the knife actuator such that said knife actuator is adapted to advance and retract the knife rod. said universal drive assembly is operably engageable with the handle assemblies of the variety of different endoscopic forceps such that actuation of the at least one movable handle of any of the variety of different forceps causes the universal drive assembly to actuate the jaw members of the end effector assembly to move between an open position wherein the jaw members are disposed in spaced relation relative to one another to a closed position for grasping tissue therebetween, said modular shaft assembly being characterized in that the shaft includes a plurality of mechanical interfaces that are configured to mate with a corresponding common plurality of mechanical interfaces disposed within the variety of endoscopic forceps; the plurality of mechanical interfaces that are configured to mate with a corresponding common plurality of mechanical interfaces disposed within the variety of endoscopic forceps are disposed on an outer periphery of the shaft; the shaft includes a bushing disposed on the shaft that mates within a corresponding mechanical interface disposed within a distal end the housing; the shaft includes a rotating assembly affixed atop the shaft for rotating the shaft relative to the handle assembly with which it is engaged; the shaft includes a knife rod disposed in said shaft and a knife actuator that slideably mounts atop a midway portion of the shaft in between the rotating assembly and the bushing; and an elongated slot is defined within the midway portion of the shaft and cooperates with the knife actuator such that said knife actuator is adapted to advance and retract the knife rod.