That's what I am running in my rear diff too, Ceramic balls by Hot Bodies, purchased from Skmotion.net using Assoc diff lube, then running the stock Avid thrust balls with AE black grease. My diff has lasted quite a long time, I am very pleased with the performance of it.
Team ORCA / ORCA USA / Pro Spec
Serpent America / Team Serpent S411 ERYX / On Point Racing OP12C, S120 / Xceed Products
Hangar 30 / Seattle RC Racers
Fasttrax Racing Series / NORA On Road Series