Did you get the 1:10 Scale Electric 4WD Touring Car Kit Catalogue, JD7164AE on the bottom right hand side of the back page, with your kit?
This details all the spares but also has excellent exploded diagrams of the various assemblies.
Inside the front cover in the right hand column there are sections titled Differentials, Turnbuckles and Anti Roll bars.
At the very bottom of the Differentials section is a very clear diagram of the Slipper Spool.
You can see that the spool pads replace the diff rings, there are no diff balls and the thrust race is fitted.