Why have the diff vent hose, line or tubing at the bottom of the vehicle where it can suck in water when playing submarine when cooling down the warm or hot diff when submerged in water?
Cooled down diff internal air space will contract hence suck in water.
The vent should be placed high as possible along with rear diff, transmission and transfer case up high in the body with a 180 degree short hook and filters attached....~~=o&o>......