I was starting to have creaking, metal on metal, and clunking noises from the back end. Upon closer look I found a lot of degradation in control arm bushings and other suspension parts. So I ended up needing to replace the upper control arms (needed new ones since no replacement possible of ball joint), lower control arms (just the bushings), sway bar links, and tie rods.
I had to take the control arms to a specialty machine shop to have the new bushings pressed because of the design. Everything went pretty well taking her apart and putting her back together but just took a lot of time. Some of the bolts were a little hard to get to. But then one of the replacement bushings in particular was a little too wide for the lower control arm bracket, and I finally figured out about the only thing I could do to get it to fit was to grind the end off 1-2 mm while it was installed in the control arm. I did get some money back from the vendor because of the mis-fit.
Here's where I sourced my parts:
https://www.ebay.com/itm/Jaguar-XJ8-...72.m2749.l2649
https://www.ebay.com/itm/NEW-Rear-Su...72.m2749.l2649
https://www.rockauto.com/en/moreinfo...1430713&jsn=30
The good news is that after my 4-wheel alignment everything is solid and feels like new.
And here's what the wear and tear on the old components looked like:

 

Some serious neglect there, I reckon. Split boots should have been found during regular servicing and replaced. A car like that would have never passed the UK roadworthiness test (our so-called MOT certificate).

 

Those look brand new compared to the rubber bits on my 2006 XJR back in 2015. The toe adjusters almost separated. Boots were all gone.
The Texas state inspection does not look at this.

 

The different lengths of replacement bushings seems to be a common problem. I had the same issue some months ago when I replaced my lower rear control arms.
Left side just perfectly into the bracket space, right side was certainly 2mm too long.
My solution was the same, took a grinder and worked away part of metal flanges of the bushing on both sides until it fit. No negative results as far as I can judge, but given the desolate conditions the bushings were in before, I probably would have felt that everything better than straight running off the road as an improvement.
As far as I saw from part catalogues there are 2 types of bushings for the lower rear wishbone, a longer and a shorter version, different by around 3 mm. Seems that especially aftermarket supplier are a bit sloppy in keeping them apart and regularly mix them.

Besides that, when looking at your picture it sure seems that it was about time to tend to the suspension

 

I've had the car less than a year and hadn't been concerned with the rear suspension until it started making a racket.

 

When I bought mine it was already "swimming" in corners, so I was warned.
After looking at your assortment there I don't really dare to check my front suspension any closer, never know what I might find.

A good general tip may also be to visit a good tyre store (or general workshop) to check on suspension. The real good ones here have suspension check devices that place the car on 4 plates and the suspension is shaken, twisted and bent in all possible directions. With these measurements they can exactly tell you which component is how far out of limits and what should be done technically.

 

An alignment is your friend. Should identify loose components.
The width of the bushing on lower control arm does vary. I replaced arms and one required shaving about a 1/4” to fit. These were OEM arms stamped Jaguar. All the Ford dealer LCA had Jaguar cast into the arm.