It'd probably need to be shades of the HTV -- namely made to approach the station, be captured by the SS Arm and maneuvered to a Common-Berthing Mechanism. In many ways, it could be simpler than the HTV -- there doesn't have to be a pressurized section or any provisions for ECLSS. Once attached to the CBM, the manipulator arm, in combination with EVAs could be used to remove the cargo and install it. Once the cargo is removed, the 'payload bay equivalent' is filled with trash, the arm un-berths it, and it maneuvers to a firey re-entry death.<br /><br />Of course it has applications even beyond the ISS completion. I have mentioned a couple of times here recently that the ISS is in deep trouble once the shuttle is retired. Long-term ISS logisitcs <b>requires</b> the shuttle -- especially with a completed station and full crew. The ATV and HTV are only stopgaps.