With reference to the split elevator, although I have never set foot onto a 74, so I cannot be sure about the accuracy, on F4's there was a split spoiler that was introduced aeons ago. The reason for this was that the single spoiler panels cracked inbetween the actuators. So to eliminate this problem they introduced split spoilers! So perhaps there is a similar reason for fitting split elevators on 74's. They say that the that the simple solutions are the best.