OP, your's is about the 3rd or 4th one that I have read that puked fluid out of the vent hose.
How much fluid did you drain out? The stock diff cover holds about 1 liter. Did you drain out less?
Couple of questions. Staying in the same gear. About 50 mph.
1. Is the noise steady state when holding a steady speed?
2. Does the noise increase when you let off the gas?
3. Does the noise increase when you increase the speed?
There is a bunch of these on the net.
https://www.onallcylinders.com/2012/...veline-noises/