I went to check the differential fluid level on my 89 XJ6 VDP. Following the Haynes Manual.

Once underneath, I found the drain plug on the very bottom. Then I looked for the fill/check plug on the back. And I actually found two plugs. On the back of the diff ... a plug at the top just has a plastic cap covering it. Is this a vent for the diff?

The lower plug on the back was directed by the Haynes Manual to be removed by a 3/8" extension. But that doesn't cut it, however a 1/2" would.

So, given that I found two plugs on the back (highly suspect the top one to be a breather/vent) and the lower plug on the back uses a 1/2" and NOT a 3/8" I need to know which is the correct check/fill plug?

I beleive it needs fluid asap.

 

the 1 with the 1/2" is the fill the other is the vent

 

And you say you don't have a crystal ball. Phewy! Lol

Thanks!

 

I dont, buy you gave a decent description, and fill until it comes out the fill hole, screw in the plug and youre done

 

So I jacked up the rear end and put it on jack stands. Unscrewed the check/fill plug and nearly half a cup of gear oil came out! Like I said, this plug isn't on the bottom of the Differential ... but on the back ... beneath another plug-type opening.

How can this much oil drain out if its the check/fill plug?

I've taken a picture which you can click on below to see what I'm seeing.

I also wrote down some numbers I have found on the Differential just for those that are so informed about these matters.

Near the plug it'self: 15U-010-022

On the Passenger Side of the Differential, a tag reading:
Genuine Exchange Product - Jaguar
Part# JLM 11880 E