04 4x4 9.75 72k I had a slight whine during acceleration that sounded to be mostly to one side. I drained it changed wheel bearings and put in new Valvoline syn 75w140 with ford FM. The oil was a little bit milky but not to bad, some powdered metal on plug but no chips or flaks of any kind. The truck now seems to be getting a louder more predominate whine. I bought the truck from a Bowtie dealer and thier shop had changed a leaky wheel seal so I have no clue what they had put in it for oil or FM. What next? Anything I can try to fix this? $$$ is tight and I dont want to rebuild the rear end now.
Any help would be great!