i can't give you a definitive answer to your questions, but i may be of help as i recently replaced the 5.125 (!) diff in my 1953 mg td with a 4.55.

moss offered a kit to do that and it fit into the old differential housing and axle. the kit included a crown ring, nut, thrust washer, two big roller bearings of different sizes, a race, a pinion shaft and a spacer. i then found a differential shop that was not too far away that had experience in the installation of MG TD differential installation (to be done correctly there is expertise and precision equipment that i did not have). once i found the shop with the diff expertise, i found another NEARBY shop that would remove the diff, store the car for four days (the time frame that the diff shop gave me for doing the job) and then re-install it.

the kit cost about $500, the shop that removed the diff, stored the car, and re-installed the diff on the car wanted $500 and the shop (the one with the MG TD diff expertise) that installed the crown ring and pinion wanted $400. once i had lined up all the materials and participants it was all over in a week. the lining up and research to gain the confidence to think it would work took me several months.

i just checked, and Moss Motors looks like they offer a number of similar kits for what they call the jaguar "early sedans". knowing what i know, i would be encouraged by what i saw. i would first ask moss about your particular car and what they can offer. if the answers are not definitive, i would get on the phone and call every jag specialist i could find and ask them. eventually you may find what you want.

there was a LOT of misinformation on the net as to what would fit what and on which car. i can be a lot to sort through. ...but i would start at moss. good luck!

 

Thanks for the tip, I'll take a look.

Wow 5.125 ratio, must have been a lot of teeth on the ring gear. Don't think I ever ran across a ratio that high.
Jjsandsms

 

ya, those engines had 54HP... even after the swap to the 4.55 i'm running 3600RPM at 55MPH. barely adequate to get on the freeway with a clear conscience.

BTW, i don't know the diff ratio in my '67 mk2, fully synchronised manual without overdrive, but it's running about 2700RPM at 62mph, which i find satisfactory.

 

Maybe Moss has persuaded Dana to make up some kits for them or gone to China.

 

Be aware of the difference between Dana and Salisbury. Although Salisbury has been owned by Dana for decades, differentials and axles from the various Salisbury factories around the world are not necessarily interchangeable with 'equivalents' made in the US by Dana.

 

My vin is 125457 so I have the earlier 3HA and the original tag with the teeth numbers is on the diff. Definitely a 4.55:1

Thanks
jjsandsms

 

With a 3HA, the way forward is definitely to search for one from a 3.8 or 3.4. They are all 4HA. If it's looking difficult to find, I'd be inclined to buy the first that looks to be in good condition at a fair price and not worry too much about 3.54 Vs 3.77 and LSD Vs non-LSD.

 

Dana do however make the standard ratio Jaguar crownwheel & pinions today.

 

The problem of confusion of parts arises because the Dana 44 looks like the Salisbury 4HA and 4HU diffs and a Dana 44 based diff was used for a while in the XJS (don't think it got into the 4-door) in the place of the 4HU. However, though they appear very similar, the parts are all different.

 

Indeed. I inquired from Dana when rebuilding my rear axle should I not be able to achieve a quiet diff. They said they could supply. Fortunately after hours of correct set up of meshing I achieved a dead silent diff. And I mean dead silent.

 

I have nearly 60 years of driving moss gearboxes in numerous Jags and I have never had to rebuild a gearbox internally.
Any problems have always been in the selectors and systems in the removable top cover.
As Glyn says they are agricultural and I might add tough as all hell.
I am in the position of being able to make direct comparisons as my 1957 MK1 has the original moss box and my 1960 Mk2 has the later Jag all synchro OD box (which is not original to the car, and I didn't do it!)
Both are ok to drive and my only remark is I would like OD on the MK1 but it's not going to happen.

As an aside.
The Toyota W58 has been a common conversion in Australia particularly changing automatic cars to manual. Dellows in Sydney can supply kits for this including bell housings and flywheels etc.

 

I agree with Bill that they are as tough as old nails. Just drive deliberately & don't be too hasty with the gear changes & the two of you will get on fine.