Hey Blackrain,

I am not positive, but I do believe the output shafts for the genesis GS039 are a much smaller than the GS208 output shafts. The inner diameter of the bearing is a 12mm for the Nemesis Differentials (page 05 of the Nemesis manual), whereas the Genesis/GST ones are the 8mm inner diameter bearing(also on page 05 of the GST manual).

To do the conversion I think you will need the GS060 Diff case cover for the smaller ID bearing, and then GS006 the spur gear for the smaller bearing. You might want to check the manual as I could be wrong.