Perhaps it is knuckle mounting bracket? The skinny one that bolts to the body near the fuel filter and to the knuckle. It's been broke and noisy since I bought the car but I bent it badly today-tire rub bad.
I need a name to shop incase the one at crazy ray's is damaged or gone.
I have searched but no real confirmed name for the part, thanks for any help.

 

The part is an assy called the HUB CARRIER and it includes the trailing arm I think you are typing about. It is only sold as a complete unit LH or RH.

I would suggest finding a good-used one at a salvage yard and learn to lift the car as far forward on the body pinched/welded seam as possible to prevent the lift devise from catching the trailing arm. It is fairly common and I have bent them back into shape more than a few times when I worked at the Jaguar dealer.

Floor jacks and twin post lifts are mostly the ones that bend the arm when the lift point is set too far back and too far IN.

bob

 

http://www.ebay.co.uk/itm/JAGUAR-X-T...RAILING-ARM-/2

The above item is for sale in the uk but it may help you to identify your damaged part.

 

Thanks for the info, in the dark last night it felt like a piece between the hub and chassis.
I hit the breaker yard this morning and found one, but did not have the proper tools to get it off, the hub nut and shock bolt were to tight.
So I found the part, now need proper 5 sided sockets to remove it.

 

Thanks Bob and Rap.
I thought I had updated this, guess not.
Entire assembly from the parts yard cost $55(hub carrier with trailing arm, hub with bearing and the axle shaft)
The bolts are tight! Otherwise was not much to it. Two bolts at font of the carrier, the shock bolt, the spring arm bolt and the 2 control arm bolts, remove brake caliper and emergency brake cable. The axle shaft pulled right out of the rear transfer case and slid right back in.