I'm not sure. In the Mustang Performance book, they had a couple dynos of different computer chips. On one of them the chip came with an octane rod, they removed the chip and made about the same power. I don't think there is any difference between using the rod or manually changing the timing. Except maybe one is easier?
Ok... I've done a little research and it appears that our dizzy's are not equipped with these octane rods.
1986 up to unkown year: Ford Aerostar, Probe, Ranger, Taurus, Tempo, Mazda B3000, Mercury Sable, Topaz
Had these octane rods. Some were even integrated with the Durasparc II ignition systems and EEC-IVs. Changing the "octane rod" (Ford calls it a Hall effect vane) would change the timing curve making either more or less agrresive dependant on the grade of gasoline available. These things were used on distributors that had centrifugal and vacuum advances. I've seen no reference to any octane rods in computer controlled distributors (doesn't mean there was't any, just means I didn't see it). These dizzy's also had TFI modules of some sort and appearantly the "octane rod" reported the crank position back to the EEC but on ly in relation to the dizzy's rotor. By changing the rod, you could advance or retard timing as much as 6* and rod length varieties came in 3 flavors, 0*, 3*, and 6*. From what I gather, it was not just an initial timing setting but a signal used by the EEC to vary the entire ignition curve. In other words: A 3* Octane rod might be worth 13* in total timing (numbers are just for example only).
Here's a pictorial that I found. I've probably seen these things before and never paid much attention to them, as I'm sure many of you have as well.