Howdy everyone —

Recently got my '84 GT vert running and am having a loud roaring noise coming from the rear. It starts as soon as the wheels turn. I have no history on this rear, so before driving I removed the differential cover to check it out and replace the leaky gasket. Oil that came out was really clean. Nothing looked concerning — no metallic sheen in the oil or debris in the bottom. Put a new gasket on and filled up with 80/90 along with a bottle of ford friction modifier.

Attached a couple of videos of me spinning the axles by hand. The noise is immediate. Never heard anything like this. If it's an axle bearing I'd be willing to change them out and keep running this unit for now. If it ends up being more complex than that, I'll probably just swap it for an 8.8 I have sitting in the corner. It would likely need rebuilding as well, but would rather put the $ in that one instead of the weaker 7.5.

Any suggestions on the noise? Thanks in advance!

https://youtu.be/ujq8ZhnxWic