I picked up a new unused set of genuine Jaguar front upper control arms at an auto jumble for $50 last weekend. The part # are XR852090 & 2091 which are for 2000 - 2003 S Types. I have a 2006 S-Type with A arm part # XR857652 & 653.
Both are types physically identical, does anyone know what the difference is and are they interchangeable ?. My suspicion is that the rubber bush compliance is probably different. For $25 each, I'll fit the later bushes if needed.

 

I doubt there is such an animal that fits the 2000-2003 S-Type unless you are talking about a UK market car, then.....perhaps. The suspension was considerably re-worked for MY2003 and my recollection is that the A-Arms are not retrofittable. I believe it was possible to remove and replace the ball joint on the earlier model, but not so on the 2003 and subsequent. If the ones you bought appear to have removeable ball joints, sorry to say, they likely won't fit your car.

Edit: Come to think of it, I believe in the UK, the facelift car was a 2002.5, so I'm more confident in my initial statement, now.

 

Yep. The control arms from the post 2003 S Type are different than the earlier ones. I checked the dimensions and the early arms are longer and the profile different than the later control arm units. They can be installed but the castor/camber and toe would be way out. I sold the early Jaguar branded arms on Craigslist and ordered the Lemfoerder control arms for the later S-Type. Fortunately its only a 1 hour job to change out the upper control arm so Im not too pissed.
I have not seen any replaceable ball joints on the front upper control arms of either version.

 

Maybe....but I wouldn't book a date for an hour after starting the upper arm R&R if I were you....

 

Took 2.5 hours to do both sides, make sure there is a T60 Torx impact bit available and then its just a few nuts and bolts. No where near as bad at the upper arms on my Audi A6, that's an sob of a job.