i installed the optional 2 speed - g84302 - in my fun factor.

if the genesis 43t fits the hub ok, i would have thought that the 39t would too - i cant see cen using 2 methods of fixing very similar gears, it would make sense for it to be the same as the optional gears for this 2 speed, which will fit either the 1st or 2nd gear hubs. it does look the same in pics, kinda hard to be sure tho