Not looking to be swonked but..... (no, not selling the truck)

[Exekiel69]

It is a hose coming out of the axle or pumpkin about 5/16 and not very long. Do not confuse it with the tank vent hose. Btw You don't need to blow the hose, You can just remove it and feel the nipple on the axle see if there is any obstruction then check the hose.

This thread i getting dirty man .

 

[Dsl_Dog_Treat]

Where is this vent you speak of located?

Drivers side half way between the backing plate and the punkin.
It should also have the splitter block for the rear brake lines as well.

The hose should run up to a clip on the frame or cross member.

Usually what happens is a wasp will plug it up to make their nest in it. Axle cavity gets heated up and can't vent due to it being plugged up.

Only other way to vent the excess pressure then is thru the axle seals.