Here's the exploded view from Traxxas of the setup.
http://www.traxxas.com/products/elec...maxx_trans.pdf
I notice they have the pinions turned around with the set screw on the motor side.
There is no spacer between the slipper and the tranny. The Revo style slipper engages a pin that goes through the input shaft.
Is this slipper really that much thicker than the original?
Hmmmmmm.......