I used the Golden Horizons diff cups and HPI gear sets. The gears are just the stockers, you just need twice as many.

I tried the heavy silicon oil and absolutely hated it. Even though I only bash and dont race I still had a heck of a time getting around the BMX track. The front tires just "pushed" though the corners giving the savage a horrible turning radius. I ended up tearing them down and just put 30wt shock oil in the front and it has been great since.

In the rear I left the heavy stuff for now because I am lazy and didnt want to tear it apart yet but I will go with something a little lighter in the back soon.