What I did was to put a hose barb on the front axle cover and ran a hose up beside the radiator even with the fender. On the rear I drilled a hole, brazed half a 1/4" pipe coupler to the cover and brazed a cover over the hole so the oil could not exit the hole to the vent. Then I ran a hose up through the floor and clamped it to the inside of the rear fender behind the passenger seat.
I have not put raised vents on the tranny and transfer cases because I have not has the occasion to drive through water up to the floor boards. and hope I don't.
I welded the two axle vent holes in the axle housing BUT, I did not plug the two vent holes for the excess grease on the bottom of the axle housing where the axle bearings are. I keep it full of grease so little if any water could get in there.
If I do something with the tranny and transfer case vents I will use the check ball type vents.