I believe others have posted that the internal gears are the same.
If not, I wonder if you could put the gears (fit) inside a Valk from a GW, and what the hear ratio might change to.
Nah, I tried it last summer on a friends bike. The ring gear & pinion has different numbers for a 'Wing than a Valk. Tried like hell to make 'em fit... ended up getting another Valk final drive.