Identify this drive train Noise? vid

My diff has an oil leak, I keep my eye on it but it runs a little low sometimes..

This noise is definitely coming from the Diff area, But i don't know if its the pinion bearing, maybe just the u-joint, or could the gears be worn? I recently replaced the pinion flange maybe 300 miles ago because i was getting vibration from the old one.

Noise started about 60 miles ago and only seems to be getting louder, Noise gets louder with speed too, accel/decel seems to have no effect on it..

https://youtu.be/EJ7BN63EyT8

 

definitely sounds like something is running dry. go ahead and grease your u-joints while youre at it. why is your diff losing gear oil? you should figure that out very soon and fix it. also, take off your drums and do the same thing. see if the noise is persistent. maybe you have a wheel seal leak and it's causing havoc on your brake shoes?