The Adwest Marles Variamatic steering box featured in the above vehicles was also used extensively in Landrovers, including Defenders.
there is about half a dozen Youtubes that feature all aspects of overhaul, changing seals etc
I would recommend watch them all if you have to do an overhaul
to the best of my knowledge, the seal kit is the universal for Jag and Landrover
these two cover most aspects
I don’t suppose we would be lucky enough to find that there is some Land Rover steering box that is configured to fit into a Jaguar. If so, these LR boxes could be at least 20-30 years newer and likely with less accumulated wear to the hard parts than our old 50-60 year Jaguar boxes.
the box design appears unchanged from MKX up till probably when LR went to rack & pinion
( if they have). Even Land Rover Discoveries had the Adwest box, as well as Defenders
One of the main gear parts differs for each application (even in each Jag)
Each case also differs
In the case of 420G, there is NO alternative, as the mounting system is of the utmost restrictive and stupid design. ( the entire engine bears down and is involved in the mounting)
The MKX (and others) mount directly to the main suspension I-beam, and are somewhat amenable to adaption…ie a Burman can be replaced by a Adwest
A cursory examination by me indicates not all Landrover casing bolts are in the same plane, however, I need to examine one in my hand, which I have been unable to do
The seal kits are the same
I just replaced my leaking Adwest steering box on the 420G, replacing the output seal did not fix the issue, so I inserted a previously rebuilt box.
Its a big job on a 420G, as the thru bolts support the engine mount, and to make matters worse, I find they changed the steering box and frame sometime between the '68 420G I personally pulled the box out of, and my mid '69 ( this is actually shown in IPL4 Parts supplement, with different part nums)
For whatever odd reason Jaguar reduced the thread size of the hole in the box from 7/16" UNC on the early box to 3/8" UNC on the later, and one of the other bolts has a spacer, replaced on later cars with a different body mount…so 2 of the 3 bolts are different
Luckily I was able to run a 3/8 bolt thru the 7/16 hole and put a nut on it to retain that one, and the others are open holes, so just adjust bolt length. One bolt is the same!
To fit the correct threaded steering box retaining bolt would require drilling out the engine and suspension mount from 3/8" to 7/16", that would be best possible way to overcome the issue
At least I appear to now have a leak free steering box, something I havent had for many years
I forgot to mention that the FSM method of removing the steering box instructs one to withdraw the steering wheel and inner column from within the vehicle.
This is not needed in my experience
rather it is easier to remove the intermediate shaft within the engine bay.
This can be accomplished by removing the upper and lower thru bolts that clamp and retain it
pry the clamped joints with a big screwdriver, and push the shaft rearwards
additional movement can be obtained by loosening the 3 steering box bolts
It is helpful to mark the spline postions each end with a good marker, as the clamp bolts will only go thru the shaft cutout in one position
when refitting, it is easier to insert the lower clamp bolt 1st