A guidance system according to various aspects of the present invention operates in conjunction with a suite of different ordnance delivery devices. In one embodiment, the guidance system comprises an interface configured to attach to the ordnance delivery devices in the suite, such as via the fuze well. The guidance system may further include a control system adapted to attempt to establish communications with a subsystem of the ordnance delivery device and operate the guidance system as a standalone guidance system if the attempt fails. The guidance system may further include a control surface interchangeably attachable, for example via an interchangeable control surface module.