I have a G3R, too and I am going to switch the Gorilla center front shaft to the Traxxas shaft as you did. I hope you could help me.
What is the part number of the shaft (#5450?)?
I notice the Gorilla center front shaft is so close to the stock servo save mount; probably 2-3 mm apart. Doesn't the Traxxas hit the mount due to the larger diameter? How to solve the porblem? Thank you.