I just had my 7.5 diff swapped out for a traction-lok and looking over the oem diff with 9000 miles this thing is covered in a fine grey film of what I believe to be metal dust from spider gear wear. Any mechanic types who might have done their own, is this normal ?

 

I had mine swapped last week. No metal dust, but the mechanic mentioed he was surprised the bearing races looked pretty worn for only 10K