RE: ***CUB BROTHERHOOD***
Crash, I think you are confusing kits.
The Goldberg is advertised at the anniversary kit. The Sig 1/5 is scale and I would think the Robart 1/5 scale gear would fit. The Goldberg Anniversary Cub is far from scale. I used the Robart 1/4 gear on my Sig 1/4 Cub and they fit great and performed very well.
Mind you I have no experience with the Sig 1/5 kit so maybe some who has built this combination will step in and report on it.
Later!!
Anthony