Glad you found the prob! I was rollling mine of the floor last night and it makes no noise, but I' using UE diffs. If you have something preloaded, it will make noise. Running them loose will not make noise when new, but they will wear and then start to make noise.

Don't use any more grease than what's needed to cover the ring gear. Excess will just make for a mess when you want to change diff oil. I'm starting out at 7K front and 1K rear.