What is this and what should it be connected to?

Going to change differential fluid (front first), and thought maybe this connected somewhere in that area. I felt around on top of the differential case and behind, but didn't feel an empty hole of any sort and the "tube" certainly isn't planning on stretching very far to anywhere else. I did see a little hole at the top just to the passenger side of the drive axle, but it's pretty tiny, really mucked up, and not "suggesting" that it wants anything inserted [yes - knock yourselves out with that one wiseacres - best description I could articulate, haha]
I added the second picture because it looks like there is a tiny opening at the end of the tube, although it's all crudded up and I didn't know if that was normal/missing something/needed to be cleaned out/etc.

Haynes was unhelpful, downloaded FSM doesn't want to open for me (diff prob haha), and CF search didn't turn anything up.
THANKS in advance

 

...there's the hole at 2 o'clock on the back of the differential

 

Looks like the differential vent tube but the top of it should be up near the cowl. Not down there.

 

forgive me... cowl? Where is the cowl located? Not the back of the differential in that other pic?
Thanks btw!

 

That is the front differential vent hose fitting. The actual vent is the white gizzy on the end of a hose near the brake booster, and against the firewall.

Pic of my hose at the differential:



.The parts catalog calls it an Axle Vent, P/N 83504653

 

Cowl. Up near the hood. Mine comes right up next to my brake booster. It's zip tied to.My upper.control arm and then is zip tied to the line holder on the firewall that goes around the engine.

 

Okay, so that hose is actually connected there? I will have to look around to find where mine goes because your beast is apparently clean and beautiful - everything on mine is covered with crap (plus, I only lift it for work if really necessary, so I'm going to do diff'l change without jacking it up).

Based on the pic of the end of my hose, does that mean I'm missing a fitting? And, does this hose end need to be cleaned out (it looks almost solid to me, which seems counter-intuitive if it's a vent of some sort).
Sorry for the DQs, I don't have an understanding of its purpose, so I'm not working with any "common sense" to figure this out.

Finally (perhaps most important at this point), do I need to figure this out stat - is it pretty bad to have this disconnected? Thanks

 

oh crap. That's the only cowl I knew of, but if that's the one you guys are talking about, then I'm clearly missing a fair length of the hose (where the hell did it go?). Because the hose goes only as far as I'm holding it in the first pic.

 

It connects into the top of the differential on the back side. Clean the tube out. It's a vent. The vents tube leads up to the top of the firewall to prevent water getting in the vent

 

Just clean it up and slide it on to the fitting on the back of the diff. Near the top

 

Thanks, will give that a shot.

 

Here'a pic that shows the front axle vent fitting at the firewall. The pic is to illustrate the bonding strap on the firewall but you can clearly see where the vent fitting is (should be). It's that white fitting with the rattle cap on it.

 

That's the other end of that hose. Gotta hook to the diff housing somewhere in order to function, eh?

 

If I'm not mistaken it looks like the OP's diff is missing the fitting for the vent hose. Just replaced mine as somehow the original hose tangled with the driveshaft and lost.

 

Please tell me it was not high on the PITA scale to replace it. 8(

In other news, if anyone's inclined to entertain another differential question...I still can't budge the last top driver's side bolt on the front differential cover. Overnight kroil, 3 pretty badly damaged knuckles now, and literally hanging all possible body weight on a box end wrench (only thing I can fit given track bar in the way in front and the narrow recess to the bolt on the cover itself), none of which have worked. I am quite willing now to run out and buy an impact gun, but I know it wouldn't fit.
Anyway, my best option at the moment is to abort the project for a couple days and maybe just keep kroil on it (although I don't know if that has any effect on the RTV undoubtedly seizing the bolt in. To this end, I figured I'd at least remove the fill plug and check/throw extra gear oil in there so I can drive it til I can complete original project.

That idea, of course, leads me to this issue. Is this what the plug is supposed to look like? The looks of it suggest that I could just stick a ratchet in there to remove. (?) However, I couldn't get it to fit and it appears that it has been similarly abused in the past (to my untrained eye, it looks stripped out a tad). QUESTION: am I missing something stupid to get the plug out, or does the appearance of the plug indicate that I'll be replacing the cover as well when (if) I get that last blasted bolt out?
*I'm reeeeally sorry on this one - dumb and basic, for sure, but my body/sanity needs a break on this haha*