A surgical instrument system, comprising: a housing including a motor-driven drive shaft, wherein said motor-driven drive shaft is configured to turn a set number of revolutions during a firing actuation; a first end effector assembly configured to be coupled to and decoupled from said housing, wherein said first end effector defines a first firing path having a first firing length, said first end effector assembly comprising: a first firing member configured to travel along said first firing path; and a first drive screw configured to be operably coupled to and operably decoupled from said motor-driven drive shaft, wherein said first drive screw is configured to engage said first firing member such that rotation of said first drive screw causes said first firing member to travel along said first firing path, and wherein said first drive screw is configured to cause said first firing member to travel said first firing length when said motor-driven drive shaft turns said set number of revolutions; and a second end effector assembly configured to be coupled to and decoupled from said housing, wherein said second end effector defines a second firing path having a second firing length, and wherein said second firing length is different than said first firing length, said second end effector assembly comprising: a second firing member configured to travel along said second firing path; and a second drive screw configured to be operably coupled to and operably decoupled from said motor-driven drive shaft, wherein said second drive screw is configured to engage said second firing member such that rotation of said second drive screw causes said second firing member to travel along said second firing path, and wherein said second drive screw is configured to cause said second firing member to travel said second firing length when said motor-driven drive shaft turns said set number of revolutions. a housing including a motor-driven drive shaft, wherein said motor-driven drive shaft is configured to turn a set number of revolutions during a firing actuation; a first end effector assembly configured to be coupled to and decoupled from said housing, wherein said first end effector defines a first firing path having a first firing length, said first end effector assembly comprising: a first firing member configured to travel along said first firing path; and a first drive screw configured to be operably coupled to and operably decoupled from said motor-driven drive shaft, wherein said first drive screw is configured to engage said first firing member such that rotation of said first drive screw causes said first firing member to travel along said first firing path, and wherein said first drive screw is configured to cause said first firing member to travel said first firing length when said motor-driven drive shaft turns said set number of revolutions; and a first firing member configured to travel along said first firing path; and a first drive screw configured to be operably coupled to and operably decoupled from said motor-driven drive shaft, wherein said first drive screw is configured to engage said first firing member such that rotation of said first drive screw causes said first firing member to travel along said first firing path, and wherein said first drive screw is configured to cause said first firing member to travel said first firing length when said motor-driven drive shaft turns said set number of revolutions; and a second end effector assembly configured to be coupled to and decoupled from said housing, wherein said second end effector defines a second firing path having a second firing length, and wherein said second firing length is different than said first firing length, said second end effector assembly comprising: a second firing member configured to travel along said second firing path; and a second drive screw configured to be operably coupled to and operably decoupled from said motor-driven drive shaft, wherein said second drive screw is configured to engage said second firing member such that rotation of said second drive screw causes said second firing member to travel along said second firing path, and wherein said second drive screw is configured to cause said second firing member to travel said second firing length when said motor-driven drive shaft turns said set number of revolutions. a second firing member configured to travel along said second firing path; and a second drive screw configured to be operably coupled to and operably decoupled from said motor-driven drive shaft, wherein said second drive screw is configured to engage said second firing member such that rotation of said second drive screw causes said second firing member to travel along said second firing path, and wherein said second drive screw is configured to cause said second firing member to travel said second firing length when said motor-driven drive shaft turns said set number of revolutions.