What is purpose of capped off brake hose?

While checking things out under rear of my truck, I noticed that the the brake line branches out three ways at the rear axle. One line to each rear wheel and one length of rubber line that is capped off. Never seen that before, just wondering why that is there?

Do you have ABS?

Sounds like you are describing the diff vent.

Sounds like you are describing the diff vent.

The reason figued it was brake line, the main brake line from front comes into a little block, that has three offshoots, one to each rear wheel and this third hose that is about two foot long, it was tucked up under the spare tire..

Do you have ABS?

Honestly, not sure, never thought to check. Will do tonight when I get home.

that is your diff vent,...that "block" is bolted to the diff with a special hollow bolt with a barb fitting for a lenth of hose to vent the diff above any water you might run through...