My thought was the previous interpretation was "Gear set" = all of the gears in the case.
i.e. you can stick a NB Miata gearset into a RX7 box. the whole gearset, not just 1 or 2 gears. However, that was a year or two ago and the phiolsophy may have changed now. Write the letter as Greg mentioned (and you did.)
Please post response.