Have a 2013 Raptor, 75K Miles. Recently started getting loud whining noise as I drive down road. Initially I thought it was road noise from my work tires that I had not rotated and balanced in a while in anticipation of getting new ones. Particularly since my back tires were pretty bald i thought it was tire noise. We’ll i just put new KO2s on and now it’s pretty clear that it’s a differential noise. Coincidentally while they were changing tires I noticed dark spot on right side of bell housing that looked like a leak. So when noise persisted, I explored that as the culprit thinking the fluid had gotten low and that was causing the noise. Yesterday I had the diff serviced, new oil put in and the mechanic said their is definitely some wear in there and some play in the pinions. He said it’s common on F150’s as the power and tires are too much for the rear end they put on them as compared to a 250 or a 2500 chevy/dodge. In a past life I had a 2002 lifted 2500 Silverado with 8.1 liter 454, 4.10 rear w/Allison tranny so i knew what he meant. I digress. So after the service, the noise is still as loud as ever. Mechanic said he’s going to give me a price on a full rebuild but wanted to get your thoughts and see if anyone has experienced the same.