I pulled my rear end on my XJ6L, and the pinion gear had no teeth left. What is the right type to switch out to? From what I read, I need a ZG d44-373. Is that correct?

 

There is a Dana brand equivalent from my understanding

Now would be the time to change the output short shaft bearings and seals

 

By the way, anyone with a noise in the rear end might want to check this. There were no teeth left, and I am not sure how my car was even able to move.

 

You can put a Dana 44 ring and pinion in the 15HU Salisbury Diff housing

I would doubt that you have 3.73 ratio, per your query on "ZG d44-373", more likely 3.58?
What is the label on the diff? - red and yellow stripe square label on the rear cover would indicate 3.58, or since you have it cracked open count the pinion and ring teeth.
But if you want 3.73, then I imagine you can change ratio without issue (I don't know if X300 electronics do any transmission ratio checks...)

Note that Dana 44 has many variants these days beyond the 'standard' 30 spline and the much older 19 spline (now there is also Super / HD / JK / etc.), which can be very confusing
I believe the main difference vs. stock Jaguar/Salisbury is the pinion outer bearing, so research carefully....
(I think pinion outer bearing is 88043/88010 for Salisbury: OD 2 11/16, ID 1 3/16
and 02872/02820 for Dana 44: OD 2 7/8, ID 1 1/8
so for Dana 44 pinion into Salisbury you likely need OD 2 11/16 and ID 1 1/8
Someone on X40/X300 surely has written up what is needed....)
Inner pinion bearing is virtually the same for Salisbury and Dana
(OD 3.0, ID 1 3/8, Width 1.1563
89410/89446 for Salisbury and 31520/31594 for Dana 44, but only difference is slight change in cup width and radii, so probably the Dana 44 ones are the way to go with Dana 44 pinion)
Also check that the ring bolt holes match the hole size for your carrier, otherwise you may need drilling/inserts

Bottom line
- do some homework before buying Dana44 parts, and don't take my word for it (I just speed read some old notes I had)
- or buy Jaguar Salisbury parts and use on-line resources to get the correct numbers (RockAuto, etc.)
- I assume if you are considering this, you are familiar with the processes involved (removing and pressing on bearings, setting pinion depth, backlash, bearing pre-load, etc.)
- otherwise it is way simpler to get a used diff and swap it in

 

There was a breakdown on an old computer of the X300 pinion gear ratios

3,56 vs, 3.77

4.11 no longer avail but if I recall the 3.2 liter engine used this ( salvage yard ? )

The transmission uses a left rear wheel speed sensor for regulation but there is a inside the transmission output rotation speed sensor ( directly related to wheel speed depending on pinion ratio )

 

I have a Diff guy rebuilding it, and I will go with the 373 and see how it works out. I am sure there are other problems in there since when I had the diff changes, a half-inch chunk was on the magnet. Since my pinion had no teeth left, I am sure that the pinon broke a few things off.

 

" a half-inch chunk was on the magnet "

It's only bad if the chunk on the magnet has a part # on it

Ensure the vent / fill plug is clear so the Diff can breathe with heated air pressure expansion above the Diff grease and not blow grease out the output seals

There are part sources on E - bay for the output bearing area but I would not trust the quality of the bearing

Item # 2 , 3 , 4 , and 5

Genuine Hub Carrier And Hub Assembly-rear For Jaguar Xj 1995 - 1997 (from 720125 To 812255) (x300) Classic | Jaguar Land Rover Classic Parts

 

Well, I thought I bought the correct ring and pinion, but my diff guy said it was wrong. Looking at the current one, it appears to have a "smooth" end, and I can't find anything like that. Can someone clue me in on what that is?

 

I'm not good on the technical terms, but my best attempt (happy to be corrected)
I'm guessing you have a Jurid coupling (big rubber donut) to connect the drive shaft to the diff.
The pinion shaft has a extended smooth rod section after the pinion nut which engages in the driveshaft to keep the two centered.
Jeep style Dana 44 pinion won't have this pinion shaft extension, so you would have to swap to a yoke and connect a corresponding flange on the driveshaft via the Universal Joint (I think similar to the setup on the X100 XKR)
If the driveshaft length is not quite compatible then you also might need some spacers.

 

wow, what a pain in the a&& that would be. Is there no one out there that makes this style so that I don't have to reinvent my drive train

 

So what are we saying? If we want to replace our ring and pinion, we must find another diff with the same setup, or we will have to make a bunch of major modifications to make this work. If that is the case, can someone let me know what they did and what parts they used? I have called around, and no one offers anything like what we need. I can get the pinion but it will not work in our applications

 

https://www.simplyperformance.com/about-us

Ask these guys. They'll sell you what you need or give you the technical advice you need. They built one for me and I've had no issues with it

 

The differentials are usually pretty tough on these cars, I would be getting a used one and swapping in the whole assembly. That being said, that does look like the correct pinion gear, I'm not sure why it wouldn't work. It is the 3.58 ratio, so is a stock ratio for a US market car.