Re: Front diff noise
Could be that when the new bearings where put into the diff, that the backlash adjustment was not (properly) set. When you drive at the speed where the noise appears and you put the tranny in Neutral, does the noise level reduze significantly? If yes, the ring gear backlash could be set wrongly.
When you have metal shavings, but don┤t see any damage/wear to pinion or ring gear, there is probably a bearing going bad.