Just some tips I learned from Dustin Evans the other day when he helped me build my diff (we share the same home track!
)
Use AE Clear and Black Grease
The stock rings are presanded, the best you will find in any kit.
Ceramic Thrust Bearings with some quality carbide main diff balls is the way to go. The stock diff balls can have problems with quality. I'm using BFAST ones and they are excellent quality.
Make sure you break the diff in properly! And DO NOT let the diff slip. It likes to be run tight
You don't need too much clear grease on the diff balls.
A little clear grease on the bottom of the rings helps keep them from slipping.