I didn't design it but, I am pretty sure the ones for front and rear diff's are up high to prevent any water getting into them, (guess that blows the theory about a one way valve I guess). The hoses are heat resistant so that is why they are not melted
and they are doing what they are intended to do vent pressure.
Also I am guessing that the drive train was assembled as much as possible before it was lifted up into the body of the truck......just a guess.
HUMTECH, give me some help here will ya
