I use a molytec silicon lube here in australia... Its rated to 200 degrees c and you can run the diff that free and it doesnt slip. Let me know if you cant get it and I will send some your way.
I dont have to replace balls and diff plates ever and it last about 10 to 15 races and then I rebuild. it takes 5 minutes to rebuild a diff and it costs me nothing but the lube.
