distal axis this arrangement stands in contrast to the situation where one mating surface faces distally and the other mating surface faces proximally like the interface between the connectors 12 22 in the fig1 embodiment described below using a sideways facing interface advantageously provides a large amount of u201c real estate u201d i e area for implementing the electrical and mechanical connections between the two assemblies moreover despite the fact that a large amount of real estate is available for the interface the overall diameter of the assemblies 60 80 when connected can remain small e g about 22 mm measured at the proximal end of second connector 70 in the embodiment illustrated in fig3 9 and does not have to increase in proportion to the number of connections that are made between the first and second connectors 90 70 fig1 a c show details of an alternative output actuator 192 that is designed to mate with an alternative control actuator 172 for use in place of the output actuator 92 and control actuator 72 discussed above in connection with the embodiments shown in fig3 9 the operation of the output actuator 192 and control actuator 172 is similar to the operation of the output actuator 92 and control actuator 72 except instead of relying on friction to transmit rotation between the face of the output actuator 92 and the face of the control actuator 72 the output actuator 192 and control actuator 172 rely on a mating mechanical interface that is designed to transmit rotation in the illustrated embodiment this mating mechanical interface comprises a slot 193 in output actuator 192 and a matching tab 173 in the control actuator 172 however persons skilled in the relevant arts will appreciate that numerous other mating configurations can be substituted therefor.