While replacing my rear leaf springs, I noticed a strange tube coming off the rear brake line junction block on top of the rear axle It just dead ends up under the body, so I'm assuming it's the vent tube for the rear diff, especially since I don't see any other vent tube. it just seems strange that it shares the same hardware with the brake line and that it comes off the axle tube. Here's a pic.

 

Yep!

 

Thanks. That's what I figured. Am I correct in assuming there's a hole in the axle tube directly under where that block is welded to the tube that allows the diff to vent? Does the gear oil flow into the axle tube, or does it just allow vapors to pass?

How about that block? Is it safe to assume they just use the same piece of metal to split the brake line since it's in a convenient location? I figured they were all connected inside the block when I first looked at it, but that would make no sense.

 

Yes.

 

Those vent hoses should have one way valves on the ends that keep water and debris from getting into both the F and R axle housings,the transmission,and the transfer case. Might want to make sure they are there and are functioning.

 

no diff oil goes into that tube. well, it shouldn't anyway.
that block isn't welded to the diff tube, it's bolted with a hollow bolt that the tube it pressed onto.

that block is a brake distribution block.

i replaced my hose with an accordion style bellow.

(the xj44 uses a solid bolt and the breather tube is located down the tube a little bit)