Teacher,
The Kyosho IGT comes with front brake only. Gotta think "spool" set-ups with this car. Good luck at 301, have some fun.
Eswlfse,
I just wipe out the paste, spray everything with WD40, wipe again, put it together, fill the diff about 7/8ths full with fluid, spin the gears to remove air bubbles and bolt it all together.
Make sure the spacer shim in the outdrive bearing goes into the same part of the diff housing( it sets pinion preload on the ring gear) Check it out before you pull the diff out of the front diff case.