My problems in the suspension haven't been with the front wishbone steel ball joints, but with the ball-type bushes in the rear suspension lower wishbones, plus the lower air spring/shock bushes. [/QUOTE]

I suspect the grease specified by Ford/Jaguar for the "Lifetime" lubricated parts is incompatible with the rubber. My same vintage cars with Lenforeder parts have zero boot deterioration.
The only parts in my suspension that were not eaten up are non-lubricated. Sway arm bushings and frame bushings.
Those ball bushes in the rear were the worst. One fell out as three separate parts once the bolt was pulled. No pressing needed.

 

That 'does not compute'.

There is too much variation among the community, even ten and more years out, between still-like-new and totally perished for there to have been anything destructive that was common to all units at point of origin.

The environment a vehicle lived through - in many cases before present owners ever had hands-on - is probably where that variation comes from.

Carfax and such as they are, I know where mine spent its time registered or 'principally garaged'. What I do NOT know is if it was actually 'garaged', how used and over what roads, if exposed to salt or stored at wintertime, or how meticulously the previous owners cared for it.

Evidence sez mine had a 'comfortable' life... and some body and paint repairs as well as that new engine.

Dice roll, those bits. Not a factory shortcoming.

Those we have as well.. but that's another story..

 

I hope you are right. But the number cars like mine are way to common. A person I know has an S type and a Lincoln LS. The same Jaguar control arms on on each. Same deterioration as my XJR. All the ball joints, bushings, and tie rod ends have cracked and split rubbers. All three are gulf coast cars.
I have an A8, the D3 models are the same vintage as a x350. I have never heard of anyone having more than one bad boot. They go through one upper control arm bushing every 60 - 70k. But is a part that is under- speced for the task. The sway bar links go too, maybe 100k. The rest of these Lemforeder arms are good for 200k. Rubber does not fall apart down here.
The previous owner of
My car had no idea how bad the suspension was. I could feel it was "loose" and heard a squeak when my wife drove by in it.
The availability of boots in England is great. Plus OEM bushings. What I found here was a collection of Uro, Beck and Arnley, and some expensive bushings from China.
New arms looked like a better option.